Sounds like your on the right track. There is a lot of info here for setting up an oven, I just got mine going. Prior to that I used an old kitchen oven. It was just to small. Don't know how big your making yours, but I made mine with three elements. Others have had a many as 12, others 4 and so on.
I have attached my wiring for my oven. I used a ground, because an electrician told me too. Don't know how much better it is or worse, but I have it.
my wiring I made colored coded, so it would be easier to follow the wires. But I use 120v and 240v with it. The contactor will work with either 120 or 240. As for the controller, mine will work with either one, as well. I have the digital controller, which you can find on Ebay for around $32.00 to $45.00. Mine is pretty elaborate as far as the internals, but more pricey. Glad I didn't have to pay for. my son got it from the electrician where he works.
Anyway, take a look at my wiring and some of the others. Some use three wire and I used four wire (gnd). I tapped into the L1/L2 and Neutral for 120v for lights, fan, controller etc. Either way will work, I guess.
You can take a look at my oven progress if you want. it's located here:
http://s80.photobucket.com/albums/j1...20Coat%20Oven/
Good luck and Have fun!
JT