Yup, and yup.

Running the joints at that angle will definitely contribute to worn boots. One thing that also seems to happen is that Isuzus that are run at factory ride height for a number of miles then lifted, is that the old worn-in boots tear shortly after the lift. Boots that are put on a lifted truck generally don't rip in such a short period of time though.

Drop brackets should help. They reduce the angle of the joints, which puts less stress on the boots. If you off-road it should also result in a stronger front driveline as the joints are most strong when they aren't bent at all. Drop brackets keeps them closer to that position.

-Tad