I'm having my steps and part of my porch replaced. Probably only take
2-3 yards. The guy doing it is a smalltime but very competent concrete
contractor and all he does is rip out the old, put the forms in, and
call the concerete truck. Mixing is, I believe, like making your own
ketchup - yeah you can do it, but there's not much point.

Good thought with the drain line.