Well you should use maximizer for one and if at all possible 2 monitors.. It will make life a lot easier. I am a warlock player my self and if u are only dual boxing then you can quest no problem. Questing is the fastest way to level, don't grind. There is a macro you can use to share quest and accept quest however it doesn't work when you have to turn in and accept the next chain so that is why i recommend dual monitor using maximizer so u can just move the mouse over and click click or use the PIP (picture in picture) functions. You shouldn't have to wait at all for a certain level before questing.. Start them both at the same time and try to keep them at the same xp so they progress at the same time. If one dies i recommend letting the other die so it doesn't get xp while the corpse doesn't. But with 2 locks i can't really see you dying at all.

Because you are only dual boxing it isn't that hard to do all the collection quests it will just take you twice as long for those.. vs 5 boxing having to do them 5 times over. There are a few collection quests I would omit because they are just terrible drop rates.

Also remember to always SS your self