Thank you; I see my mistake now. When I made that comment I hadn't yet realized that "bonvolu" was an imperative verb. :) But I'm still having trouble understanding the imperative in the second clause—according to what you said, shouldn't the sentence be "Bonvolu ne postuli ke mi faras tion!", with the regular present-tense conjugation of fari? Or does the imperativeness of the sentence carry over to the second clause in some manner?
I'm not entirely sure about this one, but googling tells me that the imperative is often used in subordinate clauses formed with ke which follow a verb expressing a command or wish, such as voli. I think that this may also apply to any verb in the imperative form, but I couldn't find direct examples. Here is one such source: https://adventuresinesperanto.wordpress.com/2012/01/23/an-interesting-mood/
Isn't it "please don't require that I must do that"? Or more literally, "please not to require that I must do that."
But I think you could say "ne postulu ke mi faru tion," because faru has its own clause. In fact, I believe "Bonvolu" is also its own clause, so you could in fact say "Bonvolu, ne postulu ke me faru tion."
Your last statement is definitely incorrect. Putting a comma after Bonvolu doesn't put it in a different clause from postuli, nor would it make sense for it to be in its own clause. It is a transitive imperative verb.
I think what you meant to say was that one could treat bonvolu as if it were an adverb-like interjection (like the English word "please" would be), but in Esperanto the parts of speech are much more strictly defined than they are in English, and an Esperanto word cannot simply navigate from one category to the other without changing in some way.
Unfortunately for this example, there is no suffix that turns Esperanto roots into interjections, so an Esperanto word that works exactly like the English "please" is impossible. The closest thing to what you were suggesting would be an adverb, so perhaps Bonvole fits the role (?).