I'm trying to understand odds, I think I got the grasp of it but not entirely sure.

1.For example the odds of an open ended straight draw (or 8 outs for that matter) are around 5:1 from flop to turn

That means I should call only when villain bets 25% of the pot, or I can semi bluff in the same way betting 25% of the pot, right?

2.The odds for turn and river together are 2:1, meaning I should use this info to decide whether I should call a flop all in.

For a bet going to the turn I should still use the 5:1 odds from flop to turn, right?