This is a good question! But as every pregnancy is different, every woman feels different and this means, that there are no rules. But I've learned that between 33th and 36th week, the belly is not to small & not to big and that the mother-to-be is still fit enough to walk for 1 hour. :)
Well, wear what you love! If you feel best in a t-shirt & blue jeans, then do ahead. If you love your beautiful long summer pregnancy dress, go for it! The most important thing is, that this is YOU in the pictures, not any other pregnant woman whatsoever. BUT (there's always a but), please do not wear BLACK (both of you). Your belly will completely vanish in black clothes. Bright colours are OK, but please not to bright and to flashy. The light will reflect these colours on your skin and it will be frustrating for you (and for me: hello photoshop) :)
You saw my photos right? :) I love everything in a natural way. But if you want to go to your hair stylist, just go! No need to, but you can... Do as you please.
I will come to you. I normally begin with a brief session inside. Just you and your naked belly. We can also do a few photos of you and your partner inside your beautiful home (but these are not naked... don't be scared), and then we go outside for a walk. The first 5 minutes, will be very unusual to you, but then, I will somehow disappear and you completely forget that I'm there... By the way, the perfect location, is a non-location. Just have a look at my portfolio and you'll find out :)
Normally it takes about 1,5 - 2 hours max. PS: if it rains, we can always shift our appointment to another available day.