If you like the feel of the long Model 98 than go for it, and grab a Flatline barrel for it.
If you would like a more compact marker, than you should go w/ Kingman's Spyders. The Compact would be the best for the money. You can get one for 89$ I believe and they are very upgradable as you improve your skills and become more interested in the sport.
I am not too familiar w/ the Genesis but i really think the Compact would be best.
Although V-Force (Shield and Morph are both very nice masks) is great, it doesn't fit certain players. Most masks are very similar and one won't perform better than the next. So go to a local proshop and try on different kinds. I would try on some V-Force, and then try on the JT Flex7 Spectra. They are really nice, and i have a pair myself.
Knee pads..? They aren't a necessity, but I guess it depends on if you have sensative (girl) knees
jk jk.. But i play soccer and lacrosse, so my knees are used to abuse, so I dont need knee pads. But after you play a few times if your knees hurt you, there are some great Redz or Rase knee pads that you can buy for real cheap, that help out a lot!
Make sure you are interested in thh sport before you buy any equipment. Renting for the first couple times you play is a wise idea.