Scripts

Does this function actually work everywhere? When I enter it into the script editor, it doesn't recognize it as a function (it doesn't highlight it in red).

Yes, it definitely works, but only in version 3.1 of the game. It seems you're writing scripts directly in the editor. It's better to use MapScriptEditor – it's clearer (it's a separate program).
Regarding the 'TALK' function:

function TALK(g1,g2) --response to choice--
answer=0;
if g1>0 then ask=1; answer=g2; end;
end;

Do I need to explain it, or is it clear? And of course, you need to make TalkBoxForPlayers modal, for example like this:

ask=0; TalkBoxForPlayers (....); while ask<=0 do sleep(2); end;

After that, you write the conditions:
if answer==1 then
else
if answer==2 then
.........
and so on.