The base dry rock you looking is something where you look at size, shape and texture. The choose the one you like best. As for the actual live rock, there can, and I do emphasize can, be a big difference between live rock types. If you simply want to seed the dry base rock with bacteria, then any decent rock will do, and you can pick any decent rock, and it will be just fine. If you want something that contains a lot of additional live on it, then the premium live rock might be a better choice.
The trick here is that all too often plain everyday live rock is often sold as "premium" live rock. Make sure you are getting what you pay for. If it's from a LFS, you can see the rock and pick and choose. If it's ordered on the net, then order from a reputable supplier.
As for rock placement, don't just stack it. It's way too easily knocked down. It's unlikely the tank will be harmed, but it's a pain to deal with. Construct a framework of one type or another and place or attach the rock to that. You need not make one massive construct. Multiple small ones often work out better. As a note, live rock usually tends to be some what oval in shape, and with out some sort of framework, it tends to look like a pile of rocks. It's also tends to not be very stable on it's own, especially if you want the various caves and such people seem to like.
Lighting choices all come down to what you want to keep in the tank. If it's fish only or FOWLR then any old lighting will do. A couple of two bulb T5 fixtures will do fine. You could even use a pair of shop lights for this. If your going to keep corals you'll need much better lighting. LED lighting is the hot lighting system right now, but expect to spend some serious money for it. If your on a budget T5 is often a better choice because of the much lower initial investment.
Assuming that you have a standard 72" long 125gal tank, for T5 lighting you would typically use two 36" long fixtures, or three 24" long fixtures. depending upon the type of corals being kept, you would have between 2 and 8 bulbs over each section of the tank.
LED lighting is a bit different because there is no really standard size fixtures, and you have to look at each manufacturer to choose what you will need. Consider going with something modular. This allows you to add more modules if you need more light, but be careful LED lighting can get expensive fast.
My preference for the sandbed is fine aragonite sand, but not the super fine sugar sand. I'm not a fan of crushed coral, or sea shells. However, I wouldn't call someone wrong that use something else.