How much should I be 3-betting? (and other questions...)

These may be stupid questions, but somebody has called me out on these possible mistakes, so:

1.) Just in terms of size, I find myself 3betting around the size of the pot. So if somebody bets 30 cents into a 60 cent pot, I would raise to 90 cents. But I heard I should be raising more. True?

2.) I have KK, raise pf ip, two callers. I cbet a flop of 557. I have been betting half the pot here. Should I bet more? Why?

3.) I have been C-betting around 50-60% of the pot. More if the flop is dangerous. But should I change my standard to at least 75%?

4.) 10nl: 77 BU, folded to me, or one caller. do i just limp here?

1. I like to raise 3x+1bb if in position and 4x-1bb out of position.
2. Standard c-bets are between 2/3 and 3/4 pot.
3. It is typical to c-bet higher on more coordinated boards.
4. Raise, you almost always have the best hand, BU, etc