My girlfriend and I are considering painting some rooms in my house,
but we want it to look professional. Here are some of the problems we
have:

There are various different textures, repairs, patches in the walls.
In order to get the most consistent look, should I use an orbital
sander on all of the wall area or try to add texture to repaired/
sanded areas to get them to match the surrounding texture? Please give
any and all advice. Thanks.