I have submitted my visitor visa application and I have biometrics on Monday. I’m hoping to get my whole application sent out on Tuesday!

I am finishing up my cover letter and have a few last questions-
How do I request multiple entries? My BF and I will possibly be going on a trip or two to Europe as stated in my cover letter. Will providing itineraries be enough? Do I need to directly write “I would like to request multiple entry”?
Do biometrics appointments have the no cell phones/electronics rule?
What is the best/cheapest way to send my documents? Fedex or UPS? I assume its recommended that I get a tracking number and insurance? Should I use express mail or is that just a personal preference?
What is a nice way to state that one of my ties for returning to the US is that I am applying for a fiance visa when I return? I'm trying to figure out a nice way to write this without sounding like I am desperate for an excuse. I don't have a job to come back to so I am most worried about my few ties to the US being a problem.
I wrote this in my cover letter...does this sound okay?
I intend to return to the US at the end of my stay on (date). I will return to the US due to strong family ties along with the desire to properly apply for permission through the fiancé visa so I may return to the UK. I understand the requirement of me being in the US to apply.Any advice?
Thank you.