That is way more than a question or two. I could write a book....
I prefer the angle drills as opposed to the right angle drills. Just easier to get the disc inside the bowl and all the way across the bottom.
When sanding the outside, I tend to use more of the center of the pad, and when sanding the inside, I tend to use more of the edge of the disc. If you try to keep the disc flat on the wood like the flat part of a plate, it gets kind of grabby because so much abrasive is in contact with the wood at one time, kind of like trying to take too big of a bite with your turning tools.
No need for reversing when using the drills. I am in the school of slow speed sanding. My drills have ranges up to about 1300 rpm, but I keep the speed to half or less. The abrasives just seem to cut better.
For rotation, I prefer to keep the edge of the pad that is in contact with the wood spinning away from or off the rim, rather than spinning into the rim. Main reason is some times it will dig in. I keep the drill going counter clockwise, so inside the bowl, I have the disc/sander, most of the time at 9 o'clock, and working with the upper edge in contact with the wood. With the outside, most of the time, I have the drill between 9 and 7:30, and working with the lower side of the disc. You can start at the rim and go down or from the center and work your way up. I think on the outside, I start at the bottom most of the time, and change that up a lot when turning the inside.
Another point is interface pads. You have a mandril which goes into the drill, and you mount your discs on it. They are fairly expensive. You can get all sorts of pads to go on it so they wear out first, and they are much cheaper than the main mandril. I keep the firm pads on for the coarse grits, up to 220 or so, then switch to a soft of medium. 120 grit on a firm pad cuts better than 80 grit on a soft pad. For the firm pads, I like the ones from Vince's WoodNWonders. They have a 1/4 round profile on the edge which do a much better job on the inside of the bowl than a square edged pad. I also prefer his abrasives. He does have a lot of info on his web site about sanding.
Another note, do not 'press' when you sand. Just the weight of the drill is more than enough pressure for sanding.
Get one of the eraser/crepe sticks for cleaning your discs. The abrasives are cutting tools, and they don't have a long life, and can not be sharpened. Learn when to toss them rather than trying to get just a little bit more out of them.