Yes you can breed a blood to a ball. It has been done, and really isn't that complicated. Just google blood python x ball python. Hybrids are always a heated topic. I personally am ok with them as long as you are very careful with your records and don't just sell offspring without proper documentation.
Could you keep a blood and a BP in the same rack? Yes but not forever, and it would take some doing.
Basically if the heat tape on the rack was set up so that it was in 2 strips, 1 for BP's and one for bloods. Each would have to be regulated by their own thermostat.
Eventually a blood is going to need at least a 48" x 24" cage, so you won't be as to keep a blood in a BP rack for very long. Not worth the trouble if you ask me.