With the cost of granite and the potential risk of cracking the slab, it's often much safer to have a pro install it. I've dealt with smaller slabs that could be handled by one person like for a vanity, but two (or more) is often better if there's room. That being said, I've installed one kitchen and two vanity sinks on slabs that I picked up from the fabricator myself. I had to make a frame to hold them vertical and steady to get them home, but I had some scraps.
Yep. This puppy is over 4' wide, and 9' long. Took 6 guys to carry it in, and weighed almost 800 lbs. Not a DIY project at all.