Look i haven't started hormones either, but from what i know....
1. if there is not much fat to work with, the existing one (regardless of
quantity) is going to be redistributed. If you want more curvy figure than
gain weight and it will settle on places typical for female (buttocks, hips etc.)
2. muscles will be reduced, but to what extent is determined by their current
volume; if there isn't much to lose than you wont
3. i am not sure about this but i think it doesn't
hope this helps, but remember that the best source of information (and the
only reliable) is your endocrinologist....
best wishes