We now know the load will be well below 100A, but since the price difference is pretty small you still want a 100A service. Makes perfect sense.
I wouldn't worry to much about voltage drop. As long as you run a 1/0 or larger it's going to be fine. Everyone gets so caught up in that 3% figure, sure you should aim to be close to that, but don't think of it as a hard limit. And to be realistic you probably won't even push 60A on a continuous basis so why figure voltage drop at 100A. Just because thats what the breaker is does NOT mean you have to use that value, I would use 75-80A.
As per usual everyone says if you direct bury a wire the world will end. If you have decent clean backfill ( No gravel or sharp rocks) then there's nothing to worry about. Tons of URD out there that is 30-40 years old with no issues. Most issues with underground wire are caused by somebody hitting the wire while digging. In which case having a conduit makes much more work than simply splicing the direct buried wire.
