While levelling to 60 I didn't find collection quests a problem - my rule of thumb was if it's a collection quest, skip it. Below 70 there are so many quests to choose from, you can't do them all anyway, so just ignore collection quests when you find them. Unfortunately the same doesn't seem to apply in Northrend - there are far more collection quests, and many that you need to finish just to open up chains of other quests.

As for a tank - if you're levelling by questing there's no real need for a tank. With my 5 shaman group I could 1 or 2 shot mobs before they even reached me. At 60 I switched one of my shamans for a RAF-free-levelled paladin, and I've not regretted the decision yet. I still 1 or 2 shot mobs, and I can now do instances too, if I choose.