live rock cant relay be rated on where it is from, you should look at what it has on it. if it is white, or almost white, dont buy it. If there is a lot of black on it, dont buy it. If it is a nice corlor of green, purple, red, or anything like that, it is probalby a good choice. Look for large pieces that dont wiegh a lot, then you will be able to have more surface area because it would mean that the rock is more porus.
and wow, do you have a lot of questions. haha. Thats a good thing.