There are several kites around that will cover you for what you are asking for - they will let you go fast and are useable on snow and water.
Board wise something long & quite stiff without much sidecut works best. I use a 162 with a wide 15 degree symmetric binding setting. Its my
Powder board when not used with the kite. normally I ride a 155cm @ 6'1 & 175lb. You can get kite specific boards if you want.
Before you get into that you need to learn to fly a power kite. get a 3-4m 4 line foil kite and read/watch some tutorials or buy a dvd if you are
having to learn solo. You will also be able to start snow kiting with this but you are quickly going to want something bigger and depowerable.
15m Naish Fly,12m & 7.5m Naish Cults, 10m & 12m Naish Parks, 9m Naish Bolt, 6m & 14m Naish X3's, 13m PL Venom, 10m & 6m Ozone
Access,
1.5m flexi Buzz, 3.5m Flexifoil Bullet, 4.7m flexi Rage, 5.6m PL Twister II, 6.6m flexi Blade, 8.0m HQ Toxic
Flexdeck Landboard, Nobile Flying Carpet 160, Airush Switch 142, Slingshot Misfit 136, Naish Monarch 134, North Whip 5'8", Fischer Skis,
Palmer & Drake Snowboards.