Find a local masonry supply place they will have bricks a lot cheaper than you'll find anywhere else. Half bricks are fine.
Wheels will be fine, the biggest thing will be keeping the evaporator level. If your running your sap level around 3/4-1" then level is critical. You don't want to scorch the pan. The lower the level in the pan, the faster you will evaporate. I'd start out about 1-1/2" till you feel comfortable how the rig runs.
ALWAYS keep a bucket of sap or water next to the evaporator just in case.
That small of an evaporator, you could lose 1/2" or so from residual heat. If you boil every day it every few days, you can leave everything in the pans and just fire up again.
You can always give away or dump extra sap. But you can't boil what you don't have.