For RvR purposes:
As a scout, you're never going to be able to survive in melee mode with a tank. Therefore, at 35, I've specced in full longbow, with shield close behind, then stealth, then low thrust.
At 50, I plan to spec high enough in shield to have slam (lvl 42 shield style), so I can stun my enemies (it's an opening style with no previous style or action required) and hopefully get far away from them so I can stealth again. Full longbow, obviously. Stealth only needs to be base at 25 (to climb keep walls) plus whatever bonuses you have. Everything else goes into thrust. I've talked to a lot of 50 scouts and most of them have said that this type of spec is best for RvR.
As far as realm abilities go, spec in aug dex 2 so you can get up to falcon eye 2. Then I'd suggest longshot and volley after that.