Summertop:

Please, Please, Please....When a player times out...
1. Flag the player as timed out.
2. Force a fold, no matter what!
3. Don't deal them in to a new hand till they unflag themselves.
4. Let existing players boot timed out players (so others can take their seat).

1. Yes!
2. I think it is actually OK to let them check in the hand on that they timed out, just do it instantly when the action comes to them and don't wait for them to return.
3. Timed out should be = sitting out, so Yes!
4. Might be an option as might be auto boot them when they timed out and the big blind comes across them.