Yes, its for the rear speakers.
I'd re-use that location if it works for you.
Actually, I just put that new speaker there on a table stand.
The right speaker is way over to the right.
I'd re-use that location if it works for you.
Actually, I just put that new speaker there on a table stand.
The right speaker is way over to the right.
Ideally, the surrounds should be near or a little above head level when in listening position (sitting down). They should be at the same level (right and left). If they are significantly higher, angling them down is helpful to get the highs to shound sharper, if you want. You may find you like the way they sound higher up anyways, especially if they are far enough away that a little vertical distance doesn't change the sound much.
Rooms are not perfect and you always have some existing limitations to work around.
I'd try placing them at a different location or two before permanently mounting them just to demo any sound differences you may notice. You may find it really doesn't matter much and you can do what is convenient. You may find that putting a speaker in a bookcase sounds better than on the wall because of the change in elevation relative to your head.
Just play around and see what works for your room! We could make recommendations all day, but in the end it is whatever works for your ears and your room layout.
Take a look at this general guide for some nice introductory info on speaker placement.
http://www.crutchfieldadvisor.com/S-Yzj9e5FbD1r/learningcenter/home/inwall_placement.html