The DC-8 is an 8 outlet box. Each socket is individually controllable. If you have high amp stuff, they make the DC-4HD (heavy duty) that allows up to 12 amps per outlet and 15 amps total. I'm not sure what amps each socket can take in the DC-8. I think the DC4HD is recommended for the IceCap ballasts, so depending on what you are using for your MHs you might need to consider this. You can poke around at their website (
http://www.neptunesys.com/). They also have a vendor forum here. You might want to ask some questions regarding your tank specifics over there just to make sure you get the right setup.
RE: the pH probes, I'm not sure what the difference is. I got the standard and it works fine. I'm not sure if the extra $ for the lab grade is worth it or not.
Jack