Not sure why you think in walls are poor sound quality, they are some AMAZING in walls out there. I REALLY like the sound of the Klipsch RCW-5's, just amazing, their RCR-5's are killer too (owned a pair once). They sound like a full floor standing speaker, go demo some at your local audio store. I just bought a set of Klipsch SCW-2 in walls for my bedroom, these are below the RCW line, they are the Synergy line, but still sound great.
Don't over look in walls, they are much nicer looking than a box stuck to the wall
I have a friend that has these with the wood panels made to match his furniture. He is very happy with the sound and his wife is happy with the look. The same company has custom speakers designed to be recessed in a wall or cabinet. They change the crossover to compensate for being flush mounted. There are good in-walls available. I don't like in-walls because they are considered fixtures and convey when you sell your house.
You can but you need to do it before you list your house. You really don't want negotiations hung up on whether or not the speakers stay. Then there is how good you or a contractor is at those patches. I've seen some jobs where even knowing where to look it was hard to see signs of repair. Unfortunately, that is rare.