I hope you don't believe that the same thing doesn't happen to us hordies. If so, you're in for a rude awakening.

anyways
1) I would never ever ever roll on a non pvp realm. You seem like a RPPVP kinda guy. Try one of those, no joke.
2) I guess I can relate with this one, as I've been horde sooo long I get a little grin on my face when I stealth into alliance zones on my rogue and the alliance music queues. It's a whole different theme to the game and somewhat feels new for a moment. To answer your question, it's not an easy answer but horde usually choose race depending on what class they roll. All horde races have a lot of flavor tbqh. When you walk into a horde city, it's like a holloween costume party every time. Anyways, here's how you choose what's best for you. Are you a min/maxer or do you choose for the looks of the race? If you're a min/maxer, there's a general consensus on what race is best for each class and I'll list them below for you. If you're in it for the looks, well you honestly can't pick a bad race because there's no really bad combination of any class-race hordeside. There's better choices, but nothing just bad like say a human mage. Now that's a horrible race for the mage class(speaking racial abilities here). Here's the list.

Min/maxer general consensus for best race per class.
Mage- undead
Shaman- tauren/orc
Warlock- orc/undead
Hunter- tauren/orc(B.Mastery spec)
Warrior- Orc(pvp)/Tauren(pve)
Priest- undead
Rogue- undead
Druid- duuuur tauren
Paladin-durrrr belf


There you have it. There are valid arguments that sway the choices differently per person, for example people who say orc is the best warlock because a warlocks only counter is rogues and wotf doesn't do crap against rogues but stun resist sure helps, and then there are those that say undead is the best warlock because in a mirror match an undead will/should kill an orc warlock every time. So, take your time and pick wisely. Don't go picking something like a belf warlock for looks if you're going to one day want to pvp. It wouldn't be a horrible choice, but skills like stun resist and wotf are generally more useful than a spell interrupt.