When working up load should I start at bottom and go up to just under max?
What increment do I go up at a time. Was going to load 5 rnds of each for testing. Do I do this with each powder and same bullet?
Then change bullets and start all over again?
I'm not picking nits here, but one of the first things one reads in most any reloading manuals is to start low and work up. This is something that applies across the board to any change in component, or firearm, no matter the make or type.
When I work up loads for rifles I usually am working with 30-06 sized cases or similar capacity ones, or something based off the .308. With the larger case capacity your pressures, depending on the specific powder your using, will usually not spike quite as fast as with the smaller case capacity rounds. So I usually work with half grain increments from start to max loads looking for accuracy. While I am working up I do NOT change anything other than the powder weight. I start with my bullets seated to fit the magazine length or the book listed OAL, which ever is the longer of the two. Once I find something that looks decent I will stat to adjust only the seating depth in around .005" increments to see if the groups will tighten up. In some cases it only takes a small amount, others I have seen as much as .100" or more making a dramatic difference in group size. With one friends rifle we tried everything we could think of to get a good group, then on a whim he set it to the book listed OAL and one hole group at 200yds. This was using the Berger bullets which at the time had everyone suggesting seating them right at or into the lands. Loaded that way they wouldn't keep three rounds out of five on a 8" paper plate at 200yds.
As for switching things around, yep sad to say that if you change bullet brands after working up you need to back off and work back up. Differences in the jackets or way the bullets may be built can or will add pressure to an already worked up load with a different bullet. IF your going to err with 45-60K of pressure 4" from your face it is always best to go lower, than higher.
I'm sorry that it can't be a plug and play sort of thing, but like mentioned above most folks don't take into consideration what sorts of pressures they are actually dealing with since it is such a small thing that is producing them. Thing is, sometimes BIG things come in very small packages. Always work up to what your goal is and be safe for yourself and the others around you. Keep in mind that IF something lets go, you might not be the only one in the line of things letting go. It could be the fellow with his 10yr old kid, or someones wife or girlfriend who is learning to shoot that, catches the brunt of the flying pieces.
