isela

Yes it takes time for them to process the payment unfortunately. It took me like 3-4 weeks for the status to change to ‘paid’ or ‘complete’ so I could have access to my application and fill it out! It’s a waiting game :(

you can request for an expedited case review based on the following reasons 
https://www.uscis.gov/forms/how-make-expedite-request
 
USCIS accepts any documents that you send with your expedited request and will not ask for further info beyond your initial submission. you can write a cover letter explaining why your case qualifies for expedited review, include any medical documents, pictures that you wish to submit. Remember that the case is reviewed by a human on the other end.  You can submit the documents to the same location where you filed your case whether its a PO BOX or an address.
 
my experience is senators are useless. they have no special powers. write a genuine cover letter explaining your situations. you can justify in the letter that the medical issues has led to job loss/ wage loss as USCIS has a medical reason as one of the expedited categories.
 

Specifics matter. Does an expedite based on financial hardship mean you definitely cannot support them? Absolutely not. Can it raise questions if you can support them? Yes. Other factors, such as if you are using a joint sponsor or not, could be factors as well.

Typically, you need a social security number of your spouse to add him/her to bank account so that may not be possible.  The goal is to provide evidence to show you have a bona fide marriage.  We front loaded our i-130 a few years ago with the following:
 
* Years worth of phone call records from calling cards, skype (screenshots) and whatsapp calls (screenshots)
* Facebook conversations and whatsapp conversations
* Pictures from all trips and, our engagement and our wedding.  Most pictures were with other people in them.  Pictures included family members of both sides
* Wedding album
* Flight itineraries and boarding passes of all trips to see each other, and hotel reservations/bills
* Greeting cards to each other (Birthdays, Christmas, Valentine's Day)
* Wedding cards from guests to us
* Life insurance policy showing applicant as beneficiary
* Retirement (401K) statement showing applicant as beneficiary
* Receipts of gifts bought for each other
* Confirmation of delivery for flowers bought for birthdays and Valentine's day
* Copy of same credit card of both beneficiary and petitioner (I added my wife's name on one of my credit cards as an authorized user [social security number is not needed for this])
 
I hope this helps.  Good luck!
 

No need to change your last name just for the i-130.  However, I do suggest not to change your last name while the i-130 is processing (ie after you submit application).
 
For Question 53, yes

I dont think so you need to change your name.  My wife dint change her's while filling the i-130.
 

Changing name is a personal decision; it's not a requirement for a CR1. 
 
Q53  Yes if denied a fiance visa.