Do paint fumes affect electronics

If you can't get all the paint out then that's a good time to think about replacing it.

The problems you might get are some paint flecks from the old paint coming off onto the newly painted surface - which will ruin the finish, or some of the old colour leaking into the new.

I wouldn't worry about the colour of the roller material itself and it is a good sign that you can still get a nap on the roller.

I have used a sprayer to paint my house before we moved in. While I can't qualify how much more paint I used, it did feel like I used more compared to rolling, but I think part of that is because it goes so quick and I may have been painting over the same areas more than I would have with a roller.

One thing to note though, when I sprayed my home, there was nothing in it. No flooring, window treatments, etc. Spraying, no matter how careful, will leave some atomized paint in the air, which will eventually hit the floor or whatever else you don't want to have paint on it. Be prepared to mask, tape, and tarp everything you don't want painted that can't be removed from the room. You will want a mask and a respirator of some kind (you probably don't need anything fancy). The mask I used had a roll of film built in it so that I could get a "clean view" when too much paint got on it. That was especially handy when doing the ceilings.

Personally, now that I have moved in, I would roll instead of spray.