Grounding a Light-tower?

Just looking to confirm... I will soon be installing a subpanel (probably 40 amp) in my shed. No metal connection to the house. Am I correct in assuming I have two options... 1) Run UF cable with a ground to the subpanel. As I understand it, because it's a separate building I must install a grounding electrode to the subpanel...or actually 2 electrodes. The grounding electrodes and the ground from the main panel would be attached to the ground bus. In this configuration I must isolate the neutral and ground busses in the subpanel. Or... 2) Run UF cable w/out ground to the subpanel. Attach two grounding electrodes to the sub. In this configuration, the neutral and ground busses would be bonded together in the subpanel. I've been studying the books and this is what I'm getting out of it. But I must say I don't think I've seen UF cable without a ground. In any case, do these sound right?

200 amps is what the home centers are stocking, not many choices over 200 amps. So...... for 1500 sq ft of home, what would be considered excessive power? 300 amps? 400 amps? (Answers only, if you have a variation of the question, start your own thread :rolleyes: )