I think Teacake has answered your first question, I'll answer the second with a screenshot:
Going back to efficiency while soloing with VT, I'm usually a holy priest, I've specced shadow for a few weeks cos I'm not raiding at the minute and I want to farm some cash up, I'm still using mostly holy gear and only have 700ish +damage, my rotation on normal mobs is MB, SW:P. MF, MF, Wand most normal mobs are down to 30% health by the time I start wanding; they die very quickly. With a single mob at 70 let's say having 7k health the most amount of mana I can gain back is 350, it just doesn't seem worthwhile using while soloing.
So ok I get a DoT which does about 2k damage over its course for around 75 mana (at best on a single normal mob) but I can gain more mana than that back while wanding and I'll be out of the FSR earlier, if you're lower level than 70 this is even less efficient but hey as always it's your choice :)
Edited, Sep 4th 2008 1:46pm by cococj