Ohms question for my rig
 

I have an Ampeg B2R rated out at 200w 8ohm and 350w 4ohm.
The cab is Crate BX410 400w 8ohm
To get the max out of this would I just get another 8ohm speaker with one plugged into the other or one out of each output on the Ampeg?

If I'm not mistaken you could run it either way to get the 4 ohm load. I would look for another Crate BX410 to have it make the most band for your buck.

Would any 8 ohm do or does it have to be the same make? Or could I add a deferent size speaker with like a 15 and tweet at 8 ohm?

I am pretty sure jlepre is right; you can daisy chain from cab to cab, or use the outputs of the head. Either way will make it 4 ohms, which with that head, is the max it could go as far as power.

I have seen the stickies but it did not make it clear in any one post.

That's why you have to read all of the posts! :D