1) Should players be allowed to play in two places at the same time (the final of a week X event AND the qualifying of a week x+1 event)?
2) Should players who lose in a Grand Slam qualifying be allowed to play a challenger in the following week?
Yes, but I think that players shouldn't be allowed to play any other tournament in the same week as GS qualies.
3) GS/IW/Miami week 2 events
Anything but the current system, it's unfair (and difficult for the managers).
I'd say that players who are still in GS by Saturday (or Sunday since these challengers usually start on Sundays) should be out of the 2nd week challengers (Q&MD).
4) Late entries & SE's
No restrictions. I see those SE spots as a kind of WC and since the number of SE spots is limited I don't have any problem with them. However, SE spots can be given according to the commitment time (not SE request time, and not ranking as it is now).
5) Doubles commitments
Commitment by one player should be enough.
6) Singles commitments by another person?
No (just because it would be easier for the managers).
7) Late entries & seedings
8) Should there be a restriction to avoid singles R1 matches between doubles partners?
9) Should picks which were sent to the person who posted the OOP be accepted?
I'd say that picks may be accepted if the person who posted OOP forwards the picks to the manager before the deadline. But if you sent picks to the wrong person you can't demand to accept them.
10) Should picks sent by e-mail be accepted?
11) Should there be a punishment for players who don't send picks?
12) Standard minimum of TT matches in first rounds (4, 5, 6, 7, no restrictions?)
Managers choise. Sometimes it happens that some cheep challenger doesn't have qualies, while TT tournament has, it that case it might be difficult to have a certain amount of matches in the first round.
13) Standardizing the OOP
No, managers choise.
14) TB method: The number of sets given to the winner when the player picks the loser (2-1, 3-2 & 3-1 losing picks) should be a tie-breaker before the SR shootout.
15) SR Shootout: Picking the correct winner or SR of a lower SR should have priority over giving a set to the winner when both players pick the loser in a higher SR?
I think we need a rule that perfect scoreline always wins.
17) Qualifying points: There should be points for qualifying wins.
Yes, at least at the event where ATP has them.
18) There should be a Team Race for the World Tour Finals.
No, but I don't really care.
19) Retirements should count for SR and shootout purposes (64 40 ret -> 64 60 win; 46 23 ret -> 46 63 60 win)?
No. I'd see it acceptable only if the retirement happend in the last set of the match (in the set which would have been the last if the retired player would have lost it).
20) Challenger choices: ranking points/entry list quality or diversity of continents/timezones?
Availablity of managers Playing tournaments where manager can't post smth on time because he is sleeping is more anoying than playing tournament with unknown players.
21) Possible exception: Accepting picks 1/2/3/4/5 minutes after the deadline?
Players can't make such demands.