is it always best to capture 2 pieces of your opponent ?

suppose my opponent leaves a single in his home, and another single somewhere else on the board. i can hit both singles but i will leave a single in his home (which will cost me quite some pips when hit) ... i am talking about early in the game when not much has changed yet

suppose your opponent has 2 singles in his home, is it wise to hit both, but leaving 2 singles of my own in his home ? (again, early in the game)

(and another question: whats a blitz?)