I agree we need clear policy here.
Yes, we can shorten the waiting time. 5 days would be fine, 3 would be too short, I think- easy to miss it on a weekend, for example. Votes are rarely added in the last couple of days.
I'd say 20 valid article edits to vote. 10's low-ish, but not out of the question. 200 is way too high, creating more issues about arbitrary "rank", plus at that size, it's hard to judge which are good edits and which are just junk... and we'd see people making an edit for each and every character they change, so as to boost their edit count. Yes, those do tend to show, but it leads to too many special rules to define what should and shouldn't be counted.
I'd allow simple Keep/Delete votes - if we (as I think is wise) go to a percentage system, it really is a vote like any other. Also, I don't believe having edited the article should in any way give someone's vote extra currency- quite the opposite. It means they're much more biased about it.
I'd prefer 80% to 75%. And if it passes the n days waiting time and doesn't have that many favoring deletion, it doesn't go to the undecided, it simply stays.
I'd also suggest that pages that were listed and kept cannot be listed again on VFD within a given time period: say, 2 weeks since the end of the last vote.