my units are to win 1 unit when playing the favorite and risking 1 unit when playing the dog.
As for the bankroll question, that depends on you. I will often risk all or most of my offshore accounts on a daily bases. This is not my bankroll though, it is just what I have available to wager with. I often risk 10 to 15 units a day. I never really set a bankroll limit in baseball, mainly because I have been fortunate to not need it. I would guess if I went down 75 units I would be done for the season.
Hopefully that will never happen.