I was recently in the middle of purchasing the Nikon 8800 and the
sales person started in on that without $400 of memory the camera
would be slow. And proceeded to try and sell $1000 of extras that
didn't seem like they were needed.
What do you need to have so that the camera will shoot back to back
fps? And allow the camera to function as designed.
This is to be expected

The profit margin on the camera itself is next to nothing if anything at all. The profit margin on all those extras is what keeps the store in business, so while you will need some of the extras and it never hurts to help support your local camera store, there's no need to purchase more than you really need.
No memory card will make your camera any faster than it already is. The write speed of the camera is limited to about 10x. Anything faster than 12x will behave exactly the same and these days it's become very difficult to find memory cards slower than 12x.
These cameras aren't exactly speed demons as compared to DSLR's with their larger buffers. Adjusting certain settings such as turning Quick Response On and Review Off in the monitor options can help, but you'll be limited to short bursts of up to about 5 frames at up to 2.5 shots per second. Afterwards, especially when shooting RAW files, you'll need to wait for the camera to catch up before you can shoot again.
Once again, these cameras aren't SLR's, but that doesn't mean they're worse than DSLR's, just different. Take some time to get to know your 8800 and work within the limitations, just as you would any other camera and you'll find it can be made to do just about anything you want it to do right out of the box.
Later on, you might want to pick up a lens converter or two, some plus diopters for macro's, a case and a tripod etc. depending on the type of photography you wish to do, but there's no need to rush. Concentrating on what you have right now will help to speed up any learning curve and give you time to weed out any unnecessary accessories from your plans.
Have fun!
--
Tom Young FCAS member
http://www.pbase.com/tyoung/