other post was getting long and I just thought of this, so rather than edit, double post...

In situation 2, if you can keep enough behind to give your opponent incorrect odds to call a turn push, but just barely, then do so. This means you get the most in on the flop that you can, while still being able to fold if the obvious draw hits.

Also means that you will be forcing your opponent to play incorrectly more often by giving him a close decision for a large amount of chips. If he folds you win the biggest pot possible, and if he calls he makes a mistake. win-win.

Applying this to situation 1 we would want to avoid going to the turn where this is the case. we would either want to be deeper, or shallower.