The first two product photos in your link look like what I have. I got mine at Home Depot. They were pretty expensive... I didn't even think to look them up on the internet for cheaper prices. In my opinion, those brackets make excellent supports for a shelf layout.
I put them on 16" centers around the room because the wall studs are on 16" centers. I used 2.5 inch and 3 inch sheetrock screws to fasten them to the studs, I used 3 screws per bracket. The 16" centers may be overkill, but I figure that too many is better than not enough. If you put them on every other stud, that would be 32" between them, which seems too far. And if you used some other distance, then there wouldn't be a stud for mounting them too. Keep in mind that sometimes wall framing is done on 24" centers which would work also in my opinion.
I used long pieces of shelf rail on the walls, don't remember the exact length, but I think you will do fine by using 24" pieces so they extend somewhat down below your 30" shelf. I made my long so I could put shelves at whatever height I wanted for storage.
To have the layout butt up against the wall, you will have to cut each rail through the center of the slots, because when you attach the shelf bracket to the rail, the top of the bracket sits below the holes in the rails. This wasn't a big deal, just put a bracket in the rail before it is mounted, mark the top of the bracket on the rail, then cut the rail off.
When mounting the rails/brackets, use a long level to make everything the same height. Also, you will have to do some "modifications" on the longer brackets because they are manufatured with a slight rise from back to front. At first, I was using a file to adjust the angle of the brackets, then I discovered that you could simply take a rag, grab ahold of the bracket, and put some weight on it, this will bend the rail in slightly and allow you to level the shelves. If you go too far, you can take a screw driver and pry the rail back out and try again. It takes some pretty good "oomph" to bend the rails like this, probably over 100 pounds.
There is a thread here at the gauge with good discussion on this, I'll find it and post a link.