Sunrise,
I'm posting posting here some details about my experience with getting diagnosed. Maybe you and others will find it a little helped as you navigate through this process yourself.

Dealing with GP can be challenging and my 1st attempt ended in my losing the doctor I had for 15 years. So think hard and prepare for your visit. Here's what I did the 2nd time around and it turned out to be a really good outcome. Disclaimer: I am simply sharing my personal experience here.

What do you say to the receptionist when you call for the appointment:
I simply told her I wanted an appointment, period. In my case I was switching GP so it was a new patient visit. I would just say you want come in for a basic health check-up.

How can you start the conversation:
When he/she enters the room, you can say that you are interested in being evaluated for possible ADHD. If your GP is like mine, he/she will likely not know much about the condition other than the basics. This is where your articles come in.

Do you have to tell your GP that you are in therapy or being treated for other "mental" issues?
I did disclosed this but I don't think you have to. I had several reasons for disclosing. 1) I wanted my new GP to oversee my overall medical care. I had just lost my old GP, and I was done messing around, I wanted quality comprehensive medical care which means I needed to have an informed MD treating the whole me. 2) I was done kissing ***, I wanted open and direct communication. I disclosed to him that I had just left my old GP, because I was not satisfied by he me over this medical concern. This really got my new GP attention and cued him into the fact that I expected that my medical care was going to be a collaborative effort, not just him telling me what to do. 3) I thought having a therapists opinion would strengthen my case. I personally told my GP that started therapy because of "family issues" and that after several sessions the therapist thought I had some clear symptoms of ADHD. I did not elaborate on what the family issue were. Since I knew he had very little personal experience with treating ADHD patient, I felt this disclosure strengthened my position a bit because psychologists see ADHD patients all the time. Also since ADHD is often not a stand alone condition, adult's often have other issues such as anxiety and depression and my GP was likely going to want evidence that these issues had been ruled out or were being treated. I will also share that I was very careful in how I phased this conversation. I did not want him to think she (a lowly psychologist) had made a diagnosis. I instead said that she had noted that I had symptoms consistent with this disorder and recommended that I consult you (my GP) to discuss this condition and possible treatment options. In my state physicians like to think they are the ones who make diagnoses.

Having said all that I think you don't necessarily have to tell the GP that you are in therapy. You can say that you've had these symptoms for a long time, were talking to a friend and that lead you to look up information on the condition...bah...bah...bah...

How to raise the medication issue
This is again a very touchy topic. You may not want to bring up your desire for medication up front. My first GP was really pissed when I requested Adderall directly, I guess he thought I was playing MD and telling him how to treat me. With my new GP I did not want to seem like I was there just to get some speed. I am overweight and I was worried that he would just think I wanted to get a stimulant for weight loss. Also, this gave me an opportunity to recognize that I WASN"T a doctor and that I did not know the best course of action. I have slight hypertension and this is a concern when choosing which medications I can take. Letting my doctor know that I respected that HE was the most qualified to make the Rx decide was important. If I wanted a collaborative relationship I had to show that I was willing to listen too.

Here is what I did. I shared my symptoms and the self assessment I found online and completed. I gave him this assessment to him for my medical file. I also openly and honestly answered his all of this questions. I explained that I had alway had these symptoms, that I had problems in school, that I am embarrassed by them and go to great length to hide them from others, etc.. And I explained why now at 42 I wanted to pursue diagnosis and treatment. I explained that I felt I had developed some good coping skills over the years but that at this point in my life I needed a little help. He asked me some very direct questions about this point in my life and I answered them honestly, including that I started therapy because I was afraid I was beginning to suffer from depression. I think the fact that I was open and showed I was serious about him overseeing my overall medical care (not necessary getting into private details of my therapy sessions) and that I would not hide important information from him. I think GP is really great about showing concern but not prying. The last time I saw him he asked me about therapy and if I needed anything else from him that could augment it. I really like my new MD :-)

Stimulant vs. Non-stimulant Medication
I let the him know that I had done some homework and reviewed different treatment plans for ADHD. Although he was not well informed on ADHD I kind of let him raise the issue of medications. I then said that the information I found seemed to indication that there are two types of medications commonly prescribed. I was well prepared but not pushy. If you really want to try the stimulant med, be prepared for the argument that it is a "controlled-substance" that is potentially addictive....bah...bah...bah.. My response to this was, I have never demonstrated addictive tendencies, I am willing to be followed closely by you, I understand the potential risks. The information I've found acknowledges that addiction is a possibility, but that stimulants such as Adderall and Ritalin have been studied for years and have been repeatedly reported to be safe and effective. I'm not asking for a year's supply, I am asking for a trial Rx for a week to see if it helps me. You and I can then decide if this is appropriate for me to continue.

This is where I made a mistake with my first physician. I did not research the non-stimulant medications so when my 1st GP suggest this, I was not well-prepared to counter it. I was the second time around! Although it may feel it is safer, I had real reservations about the Strattera. The long list of side-effect and the fact that you have to take it for a while before you realize any benefit, really turned me off.

I also didn't understand that there maybe some pressure within the medical community on GP not to prescribe stimulants. I had to accept that my GP may seek to refer me. Which in my case both GPs I dealt with were not willing to Rx a stimulant.

Dealing yet another doctor
This fact was very difficult for me because I had hid my ADHD for so long and I did not want to talk about being mentally defective to more strangers. However, my GP did not feel he was qualified to deal with ADHD alone. He listened to me, said he would act as my personal "medical director' but that he did not feel comfortable Rx medication for this condition. I live in a somewhat rural area and psychiatrists are few and far between. I did not like the idea of seeing someone just for medications. In my case my GP is part of a large medical practice and referred me a neurologist within the practice. I feel my neurologist is just a middle man (my sugar daddy). I don't know why it is OK for him to Rx me the Adderall and not my GP; but I am just dealing with it. It was simply another $15 copay that I incurred every 3-4 months. It was something I have to life with in order to get the treatment I wanted.

Well sorry for the length of this post. I am currently on Adderall XL and my symptoms are much better. It is not a cure all but it does help me. At this point I would say that my medical care has been successful.