120 volt and 240 volt will be ultimately the same price to run - you get billed by kilowatts. Which is more convenient for you and which is the room wired for?

Digital ballasts and conversion bulbs - no idea, but I personally stay away from digital for now, as they seem to be very hard on bulbs. I also don't use conversion bulbs, I run dual spectrum throughout

GH or AN - your choice. Both have proven excellent results. Which is easier to get?

The DWC club should be able to point you in the right direction for the other ???s