So a reasonable possible players someone could have drafted with last year's prospects: LT, Brees, Fitzgerald (or any other top WR). Even given the last 1st round pick (and 1st second round pick), that team would be scary!
Therefore, to keep things voilitile, I think I'd only go for 2 keeprs. However, it would be interesting if we did something like 3 keepers, but 1 of them had to be ranked below 50th for their position in the previous season.
Either way though, I think an NFL style draft is the way to go, though I think I'd go for the option of snaking after a few rounds.