Didn't I just answer this the other day???

When I got a waterpump it came with it's gasket (O-ring). Call & ask the place where you ordered it?

Cam cover gasket & spark plug rings are REALLY easy to change later. You aren't hardly wasting any effort since the VC is so easy to take off. You'll see. I generally re-use that gasket a few times until it gets hardened with heat/age. Consider those 8 little grommets under the VC mounting nuts. Sometimes it all comes together as a VC gasket 'kit'.

Anything else? External drive belts? Cam seal plug? Leaking oil anywhere else? Since you have to drain coolant maybe that's an excuse for a new T-stat? It's pretty easy to think of 2 dozen other things to spend YOUR money on...