I have some experience with racks that I can share. On my 2011, I had a Voyager rack and I really liked it. It bolted directly to the roof and did not need any rails (short or full length). I used the Voyager rack quite a bit and put two large (heavy) Pelican boxes and sometimes a spare tire up there, and I'd say it must have been a few hundred pounds. I did stop putting my spare tire up there though because I noticed the bars would dip a bit too far down close to the glass. I never actually weighed how much I had on it, but each Pelican box had to be about 75 lbs?
On my 2013, I have a full rack from Urban Offroad and it bolds either to the half rails or the full-length roof rails. Since I have the black design package, my truck came with the full-length roof rails. The Urban Offroad rack is extremely well made, and it was relatively local to me so I did not have to pay freight shipping and he installed it for free. There are some design features I liked better on the Voyager and some things I like better on my Urban Offroad rack. I think my Urban Offroad rack holds the load better, as I have the same Pelican boxes up there, along with a Hi Lift Jack, and with my spare tire a few times the bars do not bend down toward the glass in the middle nearly as much as they did on the Voyager rack. Just some food for thought.
Either way, both are great choices. They have a few more racks available, such as the Frontrunner and the Baja Rack. I really like the Baja Rack, it looks great and seems very functional - you do need the half rails though for installation. I've seen a few in person on some rigs in my Land Rover group. As for other racks, I know they have a few options, but I really like Voyager, Urban Offroad, and Baja - though I have only had experience with the two former. I will tell you, that I probably over maximize the use of my rack and it does seem to hold up well, with the caveats that I mentioned earlier.
As far as removing the reack, it is possible, but I would not recommend it on a regular basis. The racks are not difficult to install, but you want to be VERY careful that you do not crack the glass - it has happened to a few people. Maybe some other folks do remove their rack off and on depending on their needs and season, but I don't think I would go in that direction - it's a permanent fixture on my truck.
I hope that helps!
Regards, David