There is no such thing as a "snow hog" in any of the Halo games.
walmart
you press the X button as editor monitor and you go on page 2 and find warthog. If this doesn't work then you need xbox live or the map just hasn't got the vehicle.
the savanna
Orlando war mart
there are pretty nice pictures including some swiit headshots on this site. http://www.gamesradar.com/xbox360/halo-3/screenshots/g-2005000000000000000350 and here are some for halo 3 recon http://www.gamesradar.com/xbox360/halo-3-recon/screenshots/g-20081009113151703059 and some for halo wars http://www.gamesradar.com/xbox360/halo-wars/screenshots/g-20060927122334140029
I haven't seen any Energy Sword props at all on the marketplace, but if there is anyone who has it, don't hesitate to ask them by sending a message! The closest things to Halo I've found is an RC Warthog, the Halo Marine armour suit, the Guilty Spark (received when you use Halo Waypoint for the first time. This can be found in the Game Marketplace and be downloaded for free) and a few other avatar awards that can be unlocked. Finf out how to unlock them on Halo Waypoint. Hope this helps!
You will need to take it to a gunsmith or machinist to find out.
halo wars
On the last level of Halo 1 You are on the Pillar of Autumn where it crashed on the halo. Spartan 117 uses a warthog to drive to the other end of the pillar of Autumn and escape the ship. The problem is that the flood infest the Ship so driving is difficult and the ship is exploding. At the very end he reaches a blackbird ship and pilots out.
There are none
find halo wars and click it