Not sure that the process is shorter, but filing online is easy and convenient. Just answer questions and upload documents. Receive receipt immediately. Wife was a citizen in slightly more than 5 months after filing.
I'm not sure where you got that advice, but VJ history proves those notions to be wildly inaccurate. UK and France are not difficult consulates. Good luck. The K-1 immigration journey is quite a long trip to a Green Card. I would strongly suggest you get your advice from Visa Journey. We are all here to help.
I don't see a problem with handwriting. Don't overthink, and don't let the "What if" mental gymnastics drive you crazy. I'm not sure I would have chosen a K-1, but best of luck on your journey.
My advice: File the N-400 . After waiting 40 months for my wife's I-751 to be processed, she filed her N-400. 4 months later, both the I-751 and N-400 were approved in our combo interview.
I-751s are a low priority for USCIS.
No, I am not getting a refund. I had to pay in extra to the IRS again this year......but I just adjusted the Federal tax withholding from my military pension which will let me avoid owing in the future.