> I figured since both pots connected to the same leads on the
> board, then they would be in paralel. But you state this as
> series
No, i stated the text wasnt very clear (not for me anyway), and that you shouldn't connect it in parallel. Parallel will drop the resistance considerably and it won't do what you want.
If you have a 1K pot and a 100 resistance (example) , the total parallel will be 0 -> 90 Ohm as you turn the pot.
In series, the same 1K pot and 100 resistance (example) , ill got from 100 (pot at zero will not count) ->1,1K with the turn of the pot.
> I think I will ground the external case that the transformer is in,
> to the mains earth.
You can do that. But it's not required. It's really up to you. The rest sound good.
> Do you think I should pink one up @ Radio Shack and hook it up?
Not really. Those things are rated for 150 ยบ C of max temp operation. But it wont get the main current though it like the big one, so it wont heat up very much. That's why the big one has the heatsink, and the small one doesnt... and doesnt need.
But if you want to feel safe, sure, why not. Doesnt hurt
.