Hi houlajk!
I moved your thread to the no limit forums. I'm sure it will get much more attention over here.
1. This is a bit complicated. I think if you both have 15 times the amount that you CAN call. so if he raises to 45c, you'll have to call 30c and 15x30c = $4,5. So if you both $4,5 left in your stacks you can call. Problem is that this isn't a very good strategy imo. Some ppl might say I'm wrong. I just don't really want to play PP OOP in a 3b pot. Because you're going to miss the flop soo often and you'll have to fold. Now in 3b pots you're going to burn money fast this way.
2. It depends a bit what you are playing and how long you play poker.
If you are just starting off you're probably playing full ring. For a beginner in FR I suggest you follow the starting hand charts. This means limping those hands in UTG. If you are more experienced you can just raise these PP when you are more familiar with the game. I've followed the SHC for a long time and it helped me a lot.
Now if you're playing short handed games (6 handed) then limping low PP is a nono. You'll have to open raise these. But again if you are just starting out with poker I suggest that you play FR and stick to the SHC.
NOTE: This is all what I think is best, other ppl might kill me for something I said 
Best regards
RasTweet
So not bad tactic that way..