tomatoes - vine, 1 per suare, bush 9 squares per plant
zuccini - vine, 1 per suare bush - 2 squares each plant
Brussel sprouts are a cool season vegetable, and your other plants are warm season They won't grow at the same time.

You should check out the SFG book or website for spacing information.

Here is a link that might be useful: My Square Foot Garden

I will check it out, Thanks!!

Also, just to add to the conversation- don't forget about plant placement with regards to sun location. When you get your peak amount of sun light, as your plants mature, you don't want your taller, bushy plants (like your tomatoes) shading out your lower growing plants.

Have fun!