Well rogue is a great choice for warsong gulch a lot of sneeking around and running is in order for you. If i were you i would start putting talent points in the assasination talent for critcal strikes (crit for short if you get lucky you will hit a crit and do 150 % damage.) At your level you wont get very lucky as most enemies will be level 16-19. when you get in range a good strategy to get kills is to go to a enemy backstab or ambush at level 10 you should get some quick hitting daggers and items with agility bonuses. using attacks that stun your enemy and sinister strike will take them down quickly. once you get around level 17-19 you can start trying to get a group to the dungeon deadmines. it is in southern eastern kingdoms so i would take a zeppelin to unguro ( with the aid of guildmates) and move your way , dangerously, north. or you copuld get a gorup there to port you. the gear there has very good items for a rogue. wailing cavrns is a lot closer, its in barrens. hope this helps a bit.

Don't do the Zelda quest, it has you running all over the world and the XP for that quest line isn't worth it.

You will get more XP doing quest that lets you stay in the same area. Ungoro is ill advised at lv 49. I would go to Ungoro when your 51, life will be much easier. I would stay go to Felwood and do those quest there. A bunch of them are Kill Quests.

Instances are good if you have a good group. You are a bit high for ZF, but you are near the low end for Sunken Temple. I would try and get into a Sunken Temple group. You will earn pretty decent XP if your group is good and good gear as well.