1) I don't think there is a rule about this. I would say do not use the 'st' contraction as the 's' also applies to the tprs.
2) No, there are no reference indicators in UEB. I am assuming you have numbered footnotes (since you asked about numbered reference indicators). See Section 3.24 of the UEB codebook for how UEB handles numbered references. The footnotes themselves would still be at the bottom of the print page under the footnote separation line.
4)I would say yes as well...but you might want to post that part of the question on the FL ask an expert.
5) There are no Computer Braille Code Symbols in UEB. So you don't need anything on the Special Symbols page or the TN page.
6) Again, I would say yes...but that is also a question for the the FL folks. According to UEB, FL in an English context does NOT use contractions (see Section 13.2). I think your understanding of 13.6.6 is correct.
7) Again, I will defer to the FL group on that one.
Sorry I could not answer all your questions. I do know that BANA has a task force established to determine some of these issues. I will forward your questions to them just to be sure they cover things like this!
Have a great day!