My 2c

1. If you flop the nuts or close to it you can put all yur money in, the idea is not to put too much value into hands like TPTK in such cases where limpers/blinds can have pretty much anything and hit the flop in multiple ways.

Example: you hold AK raised from MP1 and got a call from Button, all else folded, flop is A62 rainbow.
You can be pretty sure you got the best hand, if you bet the flop and get called putting all your money in the pot is not bad.
Same hand but you limp from MP, button calls, SB completes, BB checks, same flop, you bet, SB and BB call, you have no idea where you stand.

4. The two cases you gave are totally different, in the first case anyone who has a K beats you, in the other case they need specifc 2 card combos (QQ/Q8), so I would go broke with the 2nd one but not the 1st

6. What is your sample size ?