Re: Floor Press
I agree with Chris, its a variant to max effort training in the bench (I've seen a lot of people use it in westside training). If you are floor pressing the same or more than a regular bench, your triceps are disproportionately strong. With the regular bench you have considerable leg drive and what I feel is more stretch reflex.
As for assistance, I use DB floor presses with a neutral grip. I feel that it trains the triceps and chest (although the rom through the pecs is less than a reg. bench). The only bench assistance I care to do now is either DB floor press or dips.