Is there a fee for the Visa Center processing the Visa? If so, how much is it? Also, I know that I will need to send a I-134 (Affidavit of Support) to my fiance , can I send that with the letter from my employer and bank now? My petition for I-129f was accepted on September 1st but hasnt arrived at the visa center yet. I want to be as proactive as possible.

At NVC they'll run security checks and assign a case number and then they'll forward the case to the embassy. No fees at this point for K1s.