How long can a player partcipate in a game and still be eligable for red shirt?

can you still have red shirt status if you play in a bowl game?

No

Players receive votes based on their performance in the game.The general public has no say so in the matter.

90 minutes

yes, a redshirt football player CAN play in games. However, if they do play, even a single down, they lose their redshirt status