I'm no expert, but I think "noch" in this sense implies that there were previous wishes, and that the "last wish" would be an additional wish. For example, I might ask for "noch ein Bier" if I want a beer after I've already had one.
Here, though, I think that the "noch" is really pretty optional, because the "other wishes" are just the wishes that the person (who, presumably, is about to be executed) has had previously throughout their life...
I would agree to you second paragraph. Actually, the "noch" doesn't make that much sense here in german, but it's more used as a phrase, so just go with it. I - as a german - still find it hard to translate, especially because of the "noch" (which apparently doesn't appear in the english version).
I would suggest "Having a last wish?" as an accepted answer (where "Having" expresses the present tense that "noch" implies here). If there are more out there who agree, I'd ask you to suggest that.
In my experience, this is (similar to) what someone behind the counter asks a customer during a transaction:
Customer: Ein Bier, bitte. Salesperson: Noch ein Wunsch? Customer: Nein, danke, das ist alles.
I admit I haven't heard the "letzter" before-- maybe if the shop is about to close? I tried "Anything else?" as a translation, and DL didn't take it. Worth a shot.
Haben Sie noch einen letzten Wunsch?" nice question. Yes, then we would ask: Noch einen letzten Wunsch? ; If you have a look to the comment above: Mein letzter Wunsch ist nicht zu sterben. , then you will see, the last wish can also stand in nominative, like 'Mein letzter Wille' which is also a synonym for the own testament.