2 Questions about Texas Hold'Em

(1) If a person does not have enough chips left in their stack to post a blind, what happens? Can they play the hand? Example: The Big Blind has to post 50 for his big blind but only has 30 in his stack. Does he just post his 30 and then the rest goes to a side pot?
(2) I know that the person who raised at the river shows their cards first. But if your cards are not better than his/hers do you have to show your losing cards? Thanks

{Moved from Hold'em Strategies}

1) Yes the rest goes into a side pot: Button calls 50, SB calls 50, BB posted 30....90 in main pot and 40 in side pot

2) No you do not have to show your losing cards, provided that someone in the hand does not request to see them (considered bad etiquette). If your hand hits the muck even if there was a request, your cards should not be shown.