spasiba

@spasiba I know this post is a bit old, but I have a very similar situation (my husband is from Turkey was here as a student then on OPT) and we are almost done with the process, just have our interview this month left. Please reach out to me if you've any more questions and I can hopefully help since we're in similar situations!

Thank you guys so so much, I really appreciate the answers
 
- K and N

This is not accurate.
 
When you have an F1 visa, what matters is not the expiration of the F1 stamp on the passport but the date on the i-20. 
 
In this case, the i-20 was finalized because she graduated and is on OPT. If she has not been without work for more than 90 days during OPT, she has 60 day grace period after the expiration of the EAD card. Otherwise, she would have to leave by the date of the EAD card.
 
Technically, because students are admitted D/S (duration of stay) to the US, she would never accrue time so there would be no ban (someone posted the law in which you can find this information in another thread). However, it would be a violation of the visa not to follow the rules. 
 
That said, I recommend that you marry before her EAD expires or, if she has grace period, before that ends, and submit AOS. The issue here is that if you decide not to marry+AOS, she will be in violation of her visa and she could get into trouble to get another visa. Even though she would not have a ban, it would be a visa violation. Plenty of people on VJ say they are going to marry/AOS and then they don't, and the foreigner ends up in a really big mess. Some marry and not AOS, and then the foreigner is also in a mess.
 
 
 

When her visa expires she will start accruing unlawful presence. After more than 180 days of unlawful presence and if AOS is not completed, she will receive an automatic 3 year ban upon leaving the country (1 year unlawful presence - 10 year ban).
However, since you are marrying and applying for AOS any unlawful presence will be ignored (for spouse of USC) and once USCIS receives the application she will enter a period of lawful stay. She cannot work or travel during this period before EAD/AP is approved - application free with aos application.
No, she will be in lawful stay.
You fill out separate i131 and I 765 but fees are waived with i485. It's issued as a combo EAD/AP card.
You can do it whenever you want. Just keep in mind the unlawful presence. In case you two change your minds and don't go through with it she will risk problems with future travels to the US.
Good luck