Cold calling out of the blinds

[Beanos]

Example) Button 19/15 raises pot, you hold KJs in the big blind. Call, raise, fold?

I know thats a general question, but i'm not looking for a specific answer. I play 1/2NL cash games, and my preflop play is generally raise/fold unless its multiway. I've noticed a lot of the videos i watch advocate calling from the blinds vs lp raisers with such hands as KJ, AJ or even as low as A9o. I have never considered playing like this because i don't know how to best play these hands oop vs pre flop raiser.

1) Is raise/fold strategy bad? (at 1/2NL)
2) Is calling with these sorts of hands something i should consider at higher levels or even at my current level?
3) If you do play these hands, what sort of flop are you looking for and are you looking to out play your opponent often to make it profitable?

Any comments would be appreciated, thanks (posted here as opposed to ssnl for info on higher levels)