Thank you for your question!
First, radio buttons: I see your reasoning in using the UEB circle shape symbol or a Nemeth circle shape for print's radio buttons depending upon which code you're in a the time. Might I suggest that you create a UEB transcriber-defined shape (Rules of UEB section 1.7.2), identify it as a "Radio button" on your Special Symbols Page, and use that for a radio button everywhere it appears? This would give your braille reader the same symbol every time a radio button is used in print.
Second, your indention for the "(1)" (and for the answer choices that follow it) is spot on. It's really your only option to indent it in 3-5 as a sub-item to item #5, since you must follow Nemeth formatting rules (and the answer choices are sub-sub items to #5 and also indented in 3-5.).
Lastly, the "(1)". I do not see why this has to be in Nemeth. It is not an enclosed list, because it only contains/consists of one item, and it is otherwise a simple number that can easily be read in either UEB or Nemeth Code. So, I would say you could leave UEB in effect in item #5 from "in words is" through the end your item #5. For item #17, I think your current Nemeth code "bubble" is appropriate.
Again, thank you for your question (and for the beautiful document). Please let me know if anything here is incomplete or unclear.
–Kyle