the memory foam would not work, first of all most people here along with other stuff i've read are pretty much in unison about the fact that foam is the worst choice for many reasons. and also i've had a memory foam mattress topper before and believe me you could not hang one of those on the wall
as for bouncing off the walls, many prefer natural reverb if its balanced and under control, although you can get it digitally too, so it shouldn't be a problem.
as for bouncing off the walls, many prefer natural reverb if its balanced and under control, although you can get it digitally too, so it shouldn't be a problem.