MBP 13" Retina HDMI/surroundsound/hdtv help?

Greeting!

Im a total newbie here, but I can see myself becoming a frequent user here!

Now to my "issues" I just bought a brand new MBP 13" retina. I absolutely love it, only issues I'm having is when I try to hook it up to my "home theatre".

I'm not a technical genius so I might be the problem here.

In any event, when I hook my MBP to my surroundsystem amplifier using HDMi I only get stereo sound, I tried different things on my amp but it only gives me stereo as an option (other options being grayed out). I dont know if this is something that can be solved somewhere on my MBP?

Other thing I noticed is that the graphics werent as good as I had hoped, it is not my internet connection where as when I watch movies via netflix or live sports the reception and graphics on my MBP is exceptional. Is there maybe a setting that I can put/change to get optimal graphics and no lagging/delay when I watch movies and such?

I appologize for not knowing to much. But I have heard good things about this forum so I hope someone can help me or redirect me to where I can get help.

Thank you in advance;)