I have not had bottom surgery, but I will answer these the best way I can.
1. Yes it is possible for some men to ejaculate as long as the Skene's Gland (female prostate) remains intact.
2. As far as I know, it's only needed to let you stand to pee. If you don't want to be able to stand to pee, then there's no need of getting it.
3. Metoidioplasties are typically small. The decision to pack lies with the man. After a metoidioplasty, some men don't feel the need to pack since they now feel complete while other men may feel the need to pack.
4. On average, 3 is the largest size erect, though I've see one be around 4 inches erect.
5. I've heard of men passing in locker rooms with a metoidioplasty. I believe part of that is also the confidence knowing that there's something in between the legs. As far as the mens room is concerned, I don't think many guys are checking out other men's penises, but yes I say it could pass in most situations.
6. Depends on how many stages you have done and what you have done. It could be a few months up to a year.
7. Yes
8. Yes, one could possibly mastubate like a cismale, just on a smaller level and not using the entire hand. Then again, not all cismales masturbate the same.
9. I haven't seen condoms in a metoidioplasty size but there's always dental dam if one is concerned.
10. Since most people who get a metoidioplasty done is not born a cismale, it is difficult to know exactly what kind of pain a cismale would have. However, where there are nerves hooked up, there is a possibility of pain.
Here's a link to a metoidioplasty surgery video I posted if you are interested.
https://www.susans.org/forums/index.php?topic=119030.0