Well... I like to align all my players before the match....
But once I forgot to select 11 to play, so my goblin team started with 14 players..!!..
We decided that it was up to my opponent to pick the players to get off the field...
Goblins versus Undead without any Big wasn't a nice thing to see....
In our small league we don't use the «Illegal Procedure» rule, but allowing the opponent to pick the players is really a good way of ensuring you don't make that mistake again....
The question about the injured player playing is more tricky... but, anyway the rule should be the same: opponent picks.
If he wants he can replay the game. if he doesn't...
Well, in that case you cann't say the injured player made a so big difference, so, he (the injured) should lost any SPPs from that match and for me it should be enought....
He cann't pass the miss to next game, because that would (probably) benefict another coach...