Try on helmets and get the one that fits your head!
Plastic helmets are just as good as kevlar ones. Shred ready and WRSI make good protective ones. Don't get full face [as Judy suggested] until you know you need one [you will know-you'll also be buying elbow pads].
In a FF you can't hear very well and at the start, its important to hear what the more experienced boaters are explaining about the next rapid.
As for sprayskirts, how dry a skirt is is not so important until you start boating in cold weather. If you see one in a sale bin that fits your boat, I suggest you get it and in a few years it will be your spare skirt. If you have the money for it, go SEALS as Judy suggested.