It depends on the rule the pool set before picks locked. The golfer has no rounds 3 and 4, so the pool fills them with a penalty, the field's worst score, or nothing at all. Here are the common approaches and exactly what TourneyRun does with each.
Many pools charge a fixed number over par for each missed round, or give the golfer the worst round in the field that day. TourneyRun's default is +8 per unplayed round, so a missed cut adds +16 to the golfer's first two rounds.
Yes, unless your pool drops him. His first two rounds count under every TourneyRun rule, Exclude included. The rule only decides what rounds 3 and 4 are worth.
In an Office Pool, yes, from the Commissioner tab, until the tournament starts. It stays locked while the tournament is in play. Salary Cap and Snake Draft pools always use Fixed Penalty (+8).
If he leaves the field before the lock, he disappears from the pick sheet and you can re-pick; the old pick stays on your entry until you do. If he is missing from the field once play starts, the pick is removed from the standings with no penalty and no replacement.
No. Exclude only leaves rounds 3 and 4 blank, and his first two rounds still count in stroke play. To take a golfer's score out entirely, the pool needs drops.
There is no rule to choose. A started golfer who misses the cut keeps the points from his two rounds and takes the -5 missed-cut penalty (1.5x at a major). No penalty rounds are added.