I'll answer the ones that I can.
Low, medium, and high is very subjective in rings, as there is no consistency between makers as to what constitutes each of those three heights. The EOP was designed to use lower rings than you would have to if you were mounting directly to the receiver, and to be more stable than using intermediate spacers/risers, etc..to use a lower ring.
Our warranty precludes the use of reloads.
A stud is mounted at the 6-o'clock position on the hand guard for mounting a bipod or sling.
Maybe some of the others here can chime in on soem of your other questions.