FBP has some additions to the core game that are exclusive to PS4 players, including the ability to dress up as Capcom characters and benefit from their powers:

Technically, Dead Rising 4 has been available on PC since its December 2016 release, but only via the Windows 10 store.  For those of us wishing for a bit broader access to the title, it hit Steam on March 14th.  At long last, our Steam friends can see us enjoying the latest Frank West adventure and chuckle at our hilarious Steam handle!

Though Dead Rising 4 was originally planned to be an Xbox Play Anywhere title (i.e. purchasing the digital copy of the Xbox One game also gives the buyer a free copy of the Windows 10 PC version), this functionality was later scrapped for the game. This left the PC version of the game in a strange limbo, where the only place PC players could buy it was the Microsoft Store. Many PC users prefer to use Steam, since they already have massive game libraries stored there. To celebrate its launch on the popular digital storefront, Capcom has released a short trailer:

The "Stocking Stuffer Holiday Pack" will automatically be added to your game if own the Season Pass and along with Frank's big red suit, the zombies are getting into the spirit with outfits that include Santa's helper elves, gingerbread men, and snowmen. New weapons, like a baseball bat wrapped in barbed wire and Chrismas lights, or the candy-stripped hammer with grenades on it called the "Candy Pain, are available, as well as a motorcycle that shoots laser beams called "Santa's Little Melter." If you don't own the Season Pass, then all of this content will cost you $4.99.

The co-op mode is being called a "co-op campaign" and takes place over the course of several episodes. Each episode takes place over the course of two days and culminates in a boss fight at the end of that second day. There are four different characters from which players can choose, each with his or own unique starting weapon, though there doesn't appear to be any difference between them as far as special skills/abilities are concerned. Speaking of skills, the skill tree in the co-op campaign is completely separate from the single-player campaign. As you kill zombies and carry out the various challenges/objectives with which you are tasked, you'll earn money and PP just like in the single-player game. That PP can then be used to acquire skills across a variety of different categories, including a "Multiplayer" one that's unique to this mode.

The Deluxe version of the game packs in at $79.99, but includes the $25 Season Pass.  So far three elements have already been announced as part of the pass:

Set 16 years after the events of Dead Rising, Frank finds himself back in the town of Willamette, CO where a fresh zombie outbreak has struck. You'll take on some new enemies, like the super-strong Evos and the super speedy Fresh, and get some new goodies for your bag of zombie-killing tricks, like EXO suits.