1. Yes, it is possible, if you defeat the enemies instead of them defeating you, you will always get an option as to what you want to do with them, if anything at all....
2. I don't really know what you mean with this, do you mean the various positions you get from the skill tree? If your question how to initiate the sexual advances yorself, you'll need to acquire the Seduce skill, after you get it the option appears in battle and under it you can do the various sexual advances you got already...
On 2, it's a bit more complicated than that I think. It's not one use of Seduce and then all of a sudden you have all the various options for the sex skills you've acquired. For example, if what you'd like to do is perform oral or give a handjob, then start with Seduce followed by whatever other skills you have that give the opponent an erection (slap ass, etc.). Once they're hard, then drop to your knees and use the Grab It skill. After that, you can do various other skills to have some fun with them.
I'm sure there are variations to this that will get the "job" done, but basically, you arouse them, then get into a suitable position, then go for it. Your combat sex skills can each only be used in certain positions, just like all your ordinary combat skills.
To get into a position where you're fucking them, I'm not so sure - I've not had any luck with that, so I'm missing something, but it will be about the same formula - turn them on, get into a suitable position, then that should open up your options. Try putting them in a Full Nelson and nipping their neck maybe? Not sure what to do after that to get to fuck them though. I'm sure someone here can offer a tip on how to do that.
