Hello there, those are all very good questions.
1. Yes, my depression has gone away. When I was having ECT (shock treatments) my depression was gone completely, ECT made so much of a difference. (I had to stop because it was making me very ill physically). Medication has helped too. I am currently on a good cocktail of meds right now and I haven't really had a really seriously depressed day in over two months!
2. No, I'm not always depressed. This has only happened when I'm going through a genuine depressive episode, which for me usually lasts a few weeks or more. These episodes usually cause me to be hospitalized until the depression starts to get better. So although sometimes it seems like it'll never go away, there is definitely hope.
3. Certainly, I have been happy!

I do have Bipolar Disorder, so sometimes I have been "too happy", but when I'm stable, I definitely experience periods of genuine happiness. Certain things make me happy, such as spending time with friends or family, exercising, listening to music, or taking a nice walk. Having a routine helps keep me happy.
4. Yes, I have experienced remission. As I mentioned earlier, my current remission has lasted more than 2 months. My longest remission was about 6 months.
5. This is probably a question that could be up for debate. Personally, I would say no, at least for the more serious types of depression. Depression is an illness that is with us forever, but it can be controlled with therapy, medication, ECT, or natural treatments. Kind of like how diabetes will always be there, but it can be controlled. I say this because there have been a couple of times where I thought I was better because my meds were working, so I stopped them...and proceeded to relapse soon after.
Thanks again for asking such good questions.

Take care!
-Melissa