Girls´ dress-code (Tehran)

Hi :-) I have 2 daughters that will be 10 next autumn - and we move to Tehran in August. I knw the main thing: they have to dress like women there, but I still have several questions about it to know how to pack, what to buy and be ready for the first weeks or months, what could I just send home and not bring with me...
I am ethusisatic about coming to Iran. We schould have no porblems with a house, we have alerady found, contacted and fixed up the school (no dress-code inside!!). I think our only problem could be the way the girls accept the "closed" dressing. I already told and explaned them, we will have a common stock of headscarfs (they find the mines always better ;-)) etc. But...
Would somebody be so kind and patient to answer my detailed questions?
Lets start (all about girls/women):
Is there any forbidden colour (red, orange)?
Can we wear open shoes (sandals etc.) without socks?
Is there any trick to make the small girls´ dressing life easier?
I always see women wearing trouses on pictures, may-I wear a long skirt?
..... and so on...
Thanks a lot .-)