FLR(M) clarification questions

I'll be filling out my FLR(M) paperwork in March 2019 but have a few more questions.  I've read through the guidelines for applying & for those of us doing the 2nd phase in 2019, it is now online ONLY for the forms.  It does say we can save & continue before submitting.  It says once we've submitted the online forms we have 10 days to post all our relevant paperwork.  So far I'm up to speed with the previous sentences.

My questions are:

The 1st day of my 28 day deadline before expiration of my permit is a Sun.  As it's an online process it's not a problem to submit on a Sun then post the paperwork on the Mon.  But----
 
1.  Do I make & go to the BIOS appt after online submission but before posting paperwork?

I don't remember 2 1/2 yrs ago if I went to the BIOS appt Before or After I posted the paperwork.  I'm presuming it was after as I'm sure I remember printing out & including a paper showing I had an appt. 

2.  Can I make a BIOS appt first before online submission?  I don't mean actually attend the BIOS before submitting ---just make the appt.

The reason for this question is--what happens if my appt for some reason (like they're overwhelmed with applicants) is after the 10 day postal deadline & I'm supposed to include something from the appt in with the paperwork.

3. Is the BIOS process the same in the UK as in the US?  I mean--Does the Royal Mail electronically send over all my info? 

In the US I didn't go to a post office but to an actual government building.

Thank you for the help.

You don't need to make an appointment for biometrics in the UK, you just show up at a post office which provides the service, not all do.

You do need the biometrics letter first which is produced as part of the online application process, I believe once you have submitted.