How well does it hold you up in the water. I'm 6'2 and 290lbs, will it keep my head up and then some?

The lifting capacity of the vest is normally shown on the labels. The more lifting capacity the higher you will be in the water.

Are these neoprene or canvas jackets you receive?

It shows a Neoprene jacket in images, but in description it is listed as Nylon PFD III, but the price is that of a Neoprene Jacket. I purchased what I thought was Neoprene, only to get Nylon PFD for $89.95. I also purchased two Nylon PFD for less than $40 each from same manufacturer O'Neill. Looking at many vest this manufacturer offers on Amazon, some through Amazon itself, they show Neoprene Jackets in images, but describe Nylon PFD III life vest in the descriptions, even mentioning Neoprene as a material in the last comment in description. DECEPTIVE MARKETING!!!