I watched some videos that told me SB should have a 3bet or fold strategy against a wide open range (especially villain is CO or BTN), reason is we can not give BB a good pot odds to call. Here is my understanding, please correct me if I'm wrong.

Assuming villain has a wide open range.
1. If villain folds to 3bet over 65%, we should 3bet with polarized range.
2. If villain folds to 3bet lower than 65%, we should 3bet with linear range like ATs+,99+,KQo+

Here is my question:
1. If villain folds to 3bet over 65% and we have mid strength hands like Q9-QJ, K9-KJ, A8-AT, J9-JQ. I think it's too strong to 3bet bluff and also not strong to 3bet for value, if we call will give BB excellent pot odds to call. How to play these type of hands preflop?
2. If we have low pocket pairs (22-88), I think we don't have high card blockers to 3bet bluff and have less play ability postflop, should we just flat to setmine?