Repainting rendered exterior walls
Yes, your plan is a good one. As suggested by Damon using a brush to apply primer will best insure a bond to the wall. A roller may do well to in the larger areas. I would not concern yourself too much with a high build primer though since the paint is intact. If there were bare spots, that would be a different story. Primer has to just get on the surface, not fully color the wall the primer color. Although if the wall will take a drastic color change, the primer can be tinted to help change it. The main thing is getting the primer on a clean sound wall, grips onto the existing surface and allows the finish to grip onto it, no matter how thick the primer goes on. Once primer "wets" the surface and dries, its job is done.

Since this is the time for a good visual inspection on the outside of the house, now is the time to really scrutinize the wood trim that is typically around doors, windows and roof overhangs. When the paint finish begins to fail in these areas, there are small cracks in the paint at the joints in the wood or at the ends. The ends of the wood are highly susceptible to taking on moisture. since the nature of the tree is to draw in water when it is growing. Seriously, it does not change after it is cut. Capillary action is what at work here. Spot check to make sure these areas are detailed with cleaning and scraping if needed and recaulk to seal the joints to seal water out.