Tell us about yourself!
hobbyking - search for 6s lipo
Yes it is possible to have a 4wd. Anyway I don't suggest this build anymore, hub motor prices have come down and these particular hub motors are still expensive and a bit weak, only my GF runs on this board now, I use a single drive, big motor with belt, if you're heavvy I suggest my latest build ( http://www.electric-skateboard.builders/t/the-mkv-2-r-spec-6372-vesc-koston-deck-lipo-6s-5a-psy-enclosure/2298/11?u=makevoid ) That uses a single 6374 sensored motor from esk8.de with a belt drive system I use Enertion's kit but there are many like DIYElectricskateboards.com , esk8.de etc... that is a good forum you should check it out.
maybe get motorbike protections, a full body armor / complete protections + full face helmet may be overkill but it's probably the safest option, also try to get / build an electric skateboard with high torque but low speed (and good braking) or one where you can limit the speed by motor controller settings. At low speed is easier to jump off the board and run, at 20-30mph, not so much ^^check electric-skateboard-parts.builders forum for more builds and gear infos
DIY Electric Skateboard
Electric Skateboard with in-wheel motors