Custom, Vivid and Standard. Custom will give you the more adjustments so you can dial in a pq closer to the incoming signal. Vivid will exaggerates all the colors.
Normally use Motion Flow Low and Cinema 2. With Motion High will give you some "soap opera". With it off, you will lose some motion resolution. However, if you are a gamer, then from what I've read, you should turn it off. I am not a gamer, if I am misinformed, someone will chime in.
I have my tv connected to DirectTV via HDMI and i don't ever get any type of pixillation. Once you get connected, go to the DirectTV menu and select the maximum resolution you plan to use (1080). If you're planning to purchase 1080p movies, select that resolution as well and you'll be set.
Let us know once you get the HD box installed. Also, just curious which model of box they bring you.