i'm a student in the uk and i want to apply for k1 visa at the us embassy in london?

i have some questions :

1_ what is gonna happen if my uk visa expried while my passport was at the us embassy in london ?? i mean what if they take a long time to issue the k1 visa for me after the interview and my uk visa expired while they have my passport at the us embassy!! am i gonna be in trouble with the uk authorities ?? or can i call the home office and let them know the situation and then they will understand my situation ??

2_ if my uk visa was about to expire or it did expire while my passport was at the us embassy. then they still would issue me the k1 visa regardless the validation of my uk visa ?? or they won't do that since i don't have a valid visa in the uk anymore!!? would the us embassy really care about my uk visa validation in this case?

3_ my gf lives and works in kentucky but when i go there we will live in florida as she has ownership of a house with her dad in florida. and she will take time off work next month to come and stay with me for 6 months here in the uk. she won't lose her job. she just will take leave to remain from her job for 6 months. will that affect the affidavit of support that she will do to sponsor me ?? or is it ok since she still has her job? and she is just on holiday?

there won't be no one to keep us updated and send us the USCIS letters in kentucky while she is here with me. so we don't want to recieve any updates from the USCIS to kentucky address. so can she put her home address as Florida as her dad will keep us updated while we are here in england and not even mention kentucky on the whole I-129 and G-325 forms?? or is it gonna be a problem if they did background check and found out that she has been living and working in kentucky the whole time?

i also read that her address and the address where i'm going to live when i get there should be the same. otherwise it will be suspecious! so what can we do about this ? shall she put 2 addresses or it doesn't really matter if she claims to live in a different state?

any help is highly appreciated and thanks in advance.