1. I would raise 100% of the time in this situation. Acting as a squeeze play, you drive out hands like JTo and other middling hands that may have limped. With so many other people in the hand it is important to get them to fold so you can deny them equity from hitting an over card (a very likely scenario given how many people are in the hand and any A down to 9 that could create a tough situation). By doing this, you’re also protecting your own equity since more often than not you will not hit a set as you are drawing to a two-outer. As mentioned earlier, 10-12 BB is a good sized raise here that should really close up the opponents’ ranges.
2. Tough spot with this many people left to act after you. With a middling hand like this it really depends on what the table dynamic looks like. Against loose players you will be good most of the time and can raise. With a tight table it’s probably best to flat as an UTG+2 raise will be suited broadways and over pairs a good chunk of the time so a 3-bet may well result in facing a 4-bet.
3. Similar situation in the last one but being close to the button I would raise most of the time. Even a very tight player will have under pairs a lot of the time in which case you are flipping and a raise can get them to fold and deny them equity. With position my general rule of thumb is to play aggressively and raise with a wider range.