How long does it take to level 4 elemental shammy from level 1 - 70 if you multi-box them all and level via a combination of quests and pure grinding?

I figure it will be a big investment in time, but I want to really make sure I am up for it.

Also what professions do you suggest benefit shammy best considering only one of the chars will actually be training the profession. I guess the others will just be following around on the same key presses but the main char will get the skill up point. ops: