you can order them all at amainhobbies.com
a good servo would be the Hi-Tec 7955TG servo.
the badlands are a great tire, they last long on all serfaces, and they get excellent grip on all serfaces to.
the proline V2 closed cell inserts would be good, waterproof and are all around good.
the badlands are for everything, like bashing and you probably will be doing some bashing on the beach with your buggy, but the badlands are also good for jumping and landing.
all 1/8 17mm buggy wheels will fit, make sure they are 17mm though. I personally like the looks of the Proline split 6 V2 wheels. But Ofna has some sick wheels also in a ton of awesome colors, http://www.ofna.com/tires-1-8-wheels.php
Spektrum is a nice choice.
Jaco foam tires are nice, idk if they make them for 1/8 buggies