Here are a few situations I have trouble with, and would appreciate help with how to determine the correct response against unknown opponents.
1. after one limper, with QQxxx on botton. - usually I fold, always in potlimit 2. after two limpers with KKxxx on the button -usually I fold in pl ,and mostly isoraise in limit 3. after one limper with two small pair, say 5533 - calling just seems to be -EV 4. post draw with AAAxx against opponent who reraised my open and stood pat , and who has been observed to pat bluff once. -seems to me that calling half the time might be close . how to calculate what to do would be much more valuable than what shuold be done. Thank you.

I like #1 (although not the word "always") and the first part of #2. I don't think the iso-raise works so much in limit against two limpers, especially at low limits.

Now that I think about it, I would flip-flop #2. The iso-raise should work better in pl, while folding KKxyz in limit (2 limpers) is likely the best choice.

#3, you are right. Fold or raise. The better you know your opponents range, the easier this decision becomes.

#4 sounds ok, I like calling the pat bluffers from time to time. The more you guess wrong, the more it will cost you, so observe your opponents 3-bet/cap frequency pre-draw and call him down a few times to get a bead on him. Mark him with descriptive notes when you get your information, and what you lose when you call him down, will turn in to profits once you discover his tendencies.