Now to continue.
Positions are important yes. There is not a best position for a really tight girl, though any position where you can spread her legs wide open helps.
If you allow her to close her legs, she has an easier time clenching (subconsciously).
If you decide to do any variation of doggy style, spread her legs so they are out side of your legs, your legs will be between her.
Do you want to cum quickly when she gives you oral? Is it something she complains about?
I personally choose when I want to cum, during intercourse and during oral. So I just enjoy the ride, and sometimes don't ejaculate (which is good for your energy levels).
Hold your breath more, and you will ejaculate faster. You likely have secondary effects of lasting longer from your breathing or other exercises you do.
Now, the play rape thing, girls have different fantasies, and that could be your girls. Though it's likely a deep down scar she has, so be wary of what you might be doing.
Some girls like to be choked, others like to be slapped. Personally I spank the girls I'm with while I'm doing them. Even if they don't like it, they mostly like it.
Is it ok to do? Well, it's up to you. There is nothing more powerful than saying NO, and telling her why you won't do that. "I will never rape a girl and play raping you is turning me off. I'll be rough, but I won't rape you babe."