have to say off the bat i'm a loyal horde player and would never roll alliance

. i just find the alliance kinda self contradicting (especially with the forsaken - i mean weren;t *they* responisible for it anyway? off topic and sorry i am very very biased and love horde it rules)
generally horde races get better pvp racials (mana tap/ arcane torrest for the blood elves as well as +5 resistence to all magic schools, war stomp. orc's stun resistence, troll's regen and priest hex-curses and most remarkable the forsaken's "will of the forsaken") which already puts the alliance at a disadvantage. alliance get apparently better pve racials (theyre the "defenders" so it makes sense) than us hordes.
in BGs on my server (maelstrom) there are more hordes than alliance. also the general consensus in outside BG's pvp is alliance can only win with numbers - i'm yet to lose to an equally equipped mage my level. most alliance wins areonly when hordes are outnumbered.
this said - BGs are pretty hard to ger honour in for whatever the alliance equivlients are to the Defiler and Warsong Outriders battegrounds (warsong and AB is it?) in the first honour/ resp is dependant on the capturing the flag and kills (best to AoE like crazy on this one) - this is the only one i still have neutral rep in and i'm usually pretty high up on the damage table. each flag gets if i remember rightly +35 rep and +15 honour
for AB its based largely on resourses and kills again - +10 rep for resources held and a small amount of honour per kill in your group unless you get the killing blow
for honour farming - AV is the way to go (and well - for pvp rewards its the best and if your horde and you get 50 AV medals you can get a white wolf from them

). +14 honour from each npc killed (its not just a direct brawl) and rep comes easy. within 2 days i was up to honoured with the Frostwolves doing just 1-1 runs a day. longer it lasts the more honour you get and it is *the* way to farm honour
as for rerolling horde - go for it.