[VS6000 (Tim)]

Hi guys, newbie here!

Need some help in buying my first setup, what I'm after is to take long exposures to capture nebula (horsehead would be awesome).

I have a 5d mk iii, 50 1.4, 16-28 2.8 and 70-200 2.8 (which I think will be the best choice). Will possibly buy a 2x teleconverter to make a 400 5.6.

So my question is, with my limited astro knowledge in finding things, What will I need to be able to find and track DSO's? So a few minutes at 200-400mm.

Goto mount? Eq5? I've heard these terms but not sure exactly what they mean..
I had in mind maybe a 1k budget.

Any help would be great, cheers!