So, after doing some studying, I've got a few questions. It would be great if someone could clarify some things for me. Now, The questions are probably kindergarden-stuff and most winning players should be able to help.

1) I was adviced to limp "not that good" hands occasionally, but I don't quite understand which hands are meant. Lets say for example, I hold 85o. This hand is certainly not that good, so I guess it would be possible to limp. But it also doesn't really flop that great, so raising or folding would be better, right?
Now lets take 56s. This hand isn't that great either, so it should be possible to limp with it. But it also can flop quite nicely, so raising would be better in order to have a bigger pot in case i flop something big...
I hope you understand my dilemma.

2) I also have some problems playing against callingstations who limp almost every hand preflop. Raising with my string hands and checking with really weak hands is easy, but how should I play medium strengh hands? Should I raise in order to punsh villain for limping and make him pay or should I check behind, since he is probably going to call anyway?

3) My third question is regarding small pocketpairs. If I have the button and my hand is 55, it's obviously a raise, but how do I react to a 3-bet? I understand that in cash-ringgames, I can call for setvalue and that I can expect to play big pots, because a reraise means a stong hand. In HU, a reraise doesn't mean always a strong hand and also stacksizes are not that deep (75bb max). Is calling for setvalue still profitable or are small pocketpairs a easy fold after a reraise?

That's it for now. I hope my writing is understandable.^^
Thanks a lot in advance for any answers.