You can pretty much use any cable you want in the walls. Especially if it is a new construction. Much easier to run wire that way. Use the cable that sounds best to you.
As far as bi-wiring, it won't hurt the sound any using a bi-wire cable, but it will be more expensive when you could buy the same cable not bi-wired. (as long as it's available.)
As far as bi-wiring, it won't hurt the sound any using a bi-wire cable, but it will be more expensive when you could buy the same cable not bi-wired. (as long as it's available.)