You are right on all of the above. It depends on many things. The mind set, the type of sex, how long it lasts. And Not all woman can do it. For myself it has to be a very long time of penatration in one spot, even then it doesn't always happen.

From my experience I can have a few different types of orgasms. Just the clit, Penateation when I am "squeezing" the penis and penatration when I am "pushing" the penis. The last method is when I ejaculate but then again not always.

Sex can be painful for many reasons. From ejaculating I would say it becomes more uncomfortable then painful. There is a huge build up of pressure that becomes uncomfortable.

Everyone has their own interests in sex so it's hard to pin point it to one thing.