As for the audio, I find I'm tweaking it a lot, trying to get the 5.1 track to sound decent though I'm using (4) 3-way speakers, so no center and no subwoofer hooked up.
Dolby Digital 5.1 relies on the center speaker for all dialogue and sound FX for every production. Occasionally you get non-essential dialogue source panned to L or R or even to a surround channel but you need to purchase a center speaker, really.
Budgets aside this sole thing will anchor your viewing experience to the dialogue coming from your screen.
Try a pawn shop to get a used one and/or a subwoofer speaker...