Bob, since you were able to strip the paper off the drywall, the drywall was probably sealed pretty well before that paper was put on. That is good news. You really don't have to prime, but it's so easy that it would not hurt to go over it with a coat of B-I-N. This will insure that the walls are still sealed and give the paint something to stick to.
Yes, you can use a brush or roller to put on a light texture with thinned drywall mud. However, keep in mind that someday you might want smooth walls again and it can get really nasty sanding them back smooth. Ask somebody who has decided they want to get rid of a textured ceiling how much fun this is. The contractors came up with texturing so small defects could be disguised. If your walls are in good shape, why do it. There are a few specialized faux finishes that lend themselves to this technique, but give this some thought before you do it.
If you do decide to, get a sheet or so of drywall, some mud, a trowel and big brushes and a roller with a couple of different nap covers and just play. See if you can come up with a texture you like and then see if you can duplicate it before you start on the walls. It's a lot cheaper and easier to go through different techniques on a sample board than to do them on a whole room and sand them off if you are not happy with the finished result. Randomness is usually the key and sometimes you have to work at it for it to look random.