First off, I'm sorry you are going through this right now. This journey is not going to be easy for you, I hope you reach some kind of closure soon.
They can't and unless you are going to court it doesn't matter. Child abuse creates holes in the memory that's why some of it could be lost in your unconscious because of the brain damage it causes.
Yes I think they are, did they make you uncomfortable at the time? Does it bother you today? Even if the answer is no to both of those questions it was still abusive because in your own words "He DID make me spoon with him and lay on him while he was drunk." forcing a child to do anything sexual is abusive. I went through the same questions before about my own childhood sexual abuse, just because you were aroused doesn't make it okay, at such a young age children cannot give informed consent. Believe it or not this incestuous sexual abuse is relatively common in dysfunctional alcoholic families. You are not alone! You might benefit from group therapy for survivors of CSA ask your T about it.
I don't think the nightmares are things that happened to you, and if you don't want to agree with it, assertively tell your T that you do not agree with it. Please take no offense by this but these dreams could also signify a hidden desire for sexual deviance you might have.
A) Bad dreams and Flashbacks are causing you distress, either you have a really good imagination or you were traumatized as a child. Take your pick.

B) In my humble opinion no. Especially not if its not distressing you and you were not bothered by it to begin with.

C) You can't, false memory syndrome is a sneaky thing, the parts where you say it is exaggerated are most likely the "false memories" the less traumatizing parts you can remember are probably real. FMS is like your unconscious mind playing tricks on you.

D) I don't know, you'd have to ask yourself that question, are you attention hungry? Do you have any motive to discredit your uncle? Is there any way you can safely confront him about it?
Its up to you, I think you need to discuss these things with your therapist more.
If it were me I would stop "digging" if the memories are there they'll come. I would try to focus more on learning coping techniques and less on the trauma, especially since you are an adult now and likely won't be traumatized like this again.
You can confront him about it if he is still around, has he recovered from his alcoholism? Or is he still drinking? Talk to your T about it before you do anything. Try to be more assertive with your T that you want to learn more coping skills for the flashbacks. I'll give you one right here.

Try some of these grounding techniques found in this link Behavior Health Resources practice the ones that best suit you.