Basking spot should be 130 - 140F.
If it's 2 feet long and eating adult mice/weaned rats, it should be fed two of those food items per day.
Humidity at 70% is good.
Permanent adult enclosure should be AT LEAST 12 x 6 x 4. These guys get a fair size and are very active, inquisitive and intelligent.
There is an excellent care sheet (for Water monitors, but the basics are the same) at vitalexotics.com. The best care sheet for varanids that I've seen on the web.
Chris