If it's an occupied house, just do a couple rooms at a time. That way you don't have the whole house tore up and annoy everyone. Flat on ceilings, Matt/eggshell on walls, satin on trims.
Your paint is NOT going to flash if you overspray onto walls. Personally though, if you're working in an occupied house with simple trim, I would just be hand painting everything. Spraying in an occupied house is both messy and stressful. It also doesn't save that much time if you have to mask everything and only doing 1 room at a time. Spraying is more productive when doing either empty houses or bulk work.Definitely in line with you on this process. I tend to overthink a lot instead of just doing it . One worry I have when spraying the trim first is the trim paint flashing where the overspray hit the wall . So you feel it will be an issue using a satin waterborne?