Hi Veena, I come from a similar situation: started on a PvE server (Alliance), switched to PvP (Now I'm Horde though). I leveled Rogue on both, and the trip from 1-70 on a PvP server isn't as different as you may think.
The one key thing to understand is that you WILL get ganked. It happens. You can always try to duck it by going to less popular areas (Like Desolace) in your early levels, but it will still happen now and again... just don't get too worked up about it.
Stranglethorn, and around Southshore will likely be the worst pre 60, then Hellfire can be a pain once you get into outlands. Besides that it really isn't a big deal. Many of the people you come apon don't want to be ganked either, and will keep to themselves (Though being a gnome, you may attract extra attention... Horde hate gnomes).
As far as a leveling build goes, just stick with combat swords, then respec to what you like for BGs later. Being on a PvP server I thought ShS would be best, as to help avoid being ganked. And though it did help to some extent, it really slowed my leveling down greatly, not to mention that if a "good" 70 wants to kill you when you're 50, they probably will... so just stick with a DPS PvE build and keep at it.