Technically, if you can get to Wintergrasp, you can fight there. However, the que system for WG gives preference to level 80 characters before any other level.
Currently you can not use a flying mount while Wintergrasp battles are going on.
Vehicles for wintergrasp are made by going to the workshop after you have reached a certain rank (kill a few people).
As of Patch 3.1 of World of Warcraft, there are no longer any "daily" quests in Wintergrasp. They've been moved to being "weekly" quests. There's a lot of information about the quests in Wintergrasp, including the random weekly quest players will want to hunt down. See the link to WoWWiki's page on Wintergrasp Quests to get the full deal.
In Dalaran's Alliance or Horde Building
In one of the recent content patches, Blizzard made it so you can Que up for Wintergrasp from the battle-masters place in capital cities. If you are chosen to participate (they also narrowed how many people can actually participate) you will be teleported to Wintergrasp a few minutes before the battle begins. On top of that, there is a portal in Dalaran at the other PvP portals, between two battlemages on top of the stairs leading up.
Bug- Aaron:Dustox lvl: 53Heracross lvl: 54Vespiquen lvl: 54Beautifly lvl: 53Drapion lvl: 57Ground- Bertha:Quagsire lvl: 55Hippowdon lvl: 59Sudowoodo lvl: 57Whiscash lvl: 55Golem lvl: 56Fire- Flint:Rapidash lvl: 58Infernape lvl: 61Steelix lvl: 57Lopunny lvl: 57Drifblim lvl: 58Psychic- Lucian:Mr. Mime lvl: 59Girafarig lvl: 59Medicham lvl: 60Alakazam lvl: 60Bronzong lvl: 63The Champion-Spiritomb lvl: 61Garchomp lvl: 66Gastrodon lvl: 60Milotic lvl: 63Roserade lvl: 60Lucario lvl: 63
Aaron Dustox, lvl 53 Heracross, lvl 54 Vespiquen, lvl 54 Beautifly, lvl 53 Drapion, lvl 57 Bertha Quagsire, lvl 55 Hippowdon, lvl 59 Sudowoodo, lvl 57 Whiscash, lvl 55 Golem, lvl 56 Flint Rapidash, lvl 58 Infernape, lvl 61 Steelix, lvl 57 Lopunny, lvl 57 Drifblim, lvl 58 Lucian Mr. Mime, lvl 59 Girafarig, lvl 59 Medicham, lvl 60 Alakazam, lvl 60 Bronzong, lvl 63 Cynthia Spiritomb, lvl 61 Garchomp, lvl 66 Gastrodon, lvl 60 Milotic, lvl 63 Roserade, lvl 60 Lucario, lvl 63
The first time you fight him, Juan has: lvl 41 Luvdisc, lvl 41 Whiscash, lvl 43 Sealeo, lvl 43 Crawdaunt, and lvl 46 Kingdra. The Second time you fight him he has: lvl 46 poliwag, lvl 46 Whiscash, lvl 48 Walrein, lvl 48 Crawdaunt, and lvl 51 Kingdra. The Third Time You fight him he has: lvl 50 Poliwhirl, lvl 51 Whiscash, lvl 53 Walrein, lvl 53 Crawdaunt, and lvl 56 Kingdra. The fourth time you fight him he has: lvl 56 Lapras, lvl 58 Whiscash, lvl 56 Poliwhirl, lvl 58 Walrein, lvl 58 Crawdaunt, and lvl 61 Kingdra. The final time you fight him he has: lvl 61 Lapras, lvl 63 Whiscash, lvl 61 Politoed, lvl 63 Walrein, lvl 63 Crawdaunt, and lvl 66 Kingdra.
First you will battle:Will- Xatu lvl. 40, Jynx lvl. 41, Exegutor lvl. 41, Slowbro lvl. 41, another Xatu lvl. 42.Koga- Ariados lvl. 40, Venomoth lvl. 41, Forretress lvl. 43, Muk lvl. 42, Crobat lvl. 44.Bruno- Hitmontop lvl. 42, Hitmonlee lvl. 42, Hitmonchan lvl. 42, Onix lvl. 43, Machamp lvl. 46.Karen- Umbreon lvl. 42, Vileplumpe lvl. 42, Gengar lvl. 45, Murkrow lvl. 45, Houndoom lvl. 47Champion Lance- Gyardos lvl. 44, 2 Dragonites lvls. 49, Aerodactyl lvl. 48, Charizard lvl. 48, Dragonite lvl. 50.
first aaron lvl 53 dustox lvl 53 beautifly lvl 54 vespiqueen lvl 54 heracross lvl 57 drapion second bertha lvl 55 quagsire lvl 55 whiscash lvl 56 golem lvl 57 sudowoodo lvl 59 hippowdon third flint lvl 58 rapidash lvl 57 steelix lvl 58 drifblim lvl 57 lopunny lvl 61 infernape fourth lucian lvl 59 mr. mime lvl 59 girafarig lvl 60 medicham lvl 60 alakazam lvl 63 bronzong Chapion cynthia lvl 61 spiritomb lvl 60 roserade lvl 60 gastrodon lvl 63 lucario lvl 63 milotic lvl 66 garchomp Good Luck
The Pokemons are: Lorelei: (Ice Pokemons) Dewgong lvl 52 Cloyster lvl 51 Slowbro lvl 52 Jynx lvl 54 Lapras lvl 54 Bruno: (Fight/Rock) Onix lvl 51 Hitmonchan lvl 53 Hitmonlee lvl 53 Onix lvl 54 Machamp lvl 56 Agatha: (Ghost) Gengar lvl 54 Golbat lvl 54 Haunter lvl 53 Arbok lvl 56 Gengar lvl 58 Lance: (Dragon) Gyarados lvl 56 Dragonair lvl 54 Dragonair lvl 54 Aerodactyl lvl 58 Dragonite lvl 60 Rival ? (Name) Pidgeot lvl 59 Alakazam lvl 57 Arcanine lvl 59 Rhydon lvl 59 Exeguttor lvl 61 Blastoise Charizard (Depending on your starter) lvl 63 Venusaur Good Luck!!!! ^^
In the Hoenn region.