Kickspace heater in 2 pipe direct return system

Spudwrench

Happy Holidays!
I'd like to install a Myson toe-kick heater in an existing 2-pipe direct return HW system. The kitchen is at the "end of the run" - can I just install a flow balancing valve in series with the heater, and pipe in and out of the heater and rebalance the rest of the system as needed? The diagram Myson provides shows what appears to be two Monoflo T's on a 2 pipe direct return system, which doesn't make sense to me- I can understand why you'd want to do that on a series loop system, but not on a direct return. Besides, how would you install Monoflos on the end of a run?
My second question is how do you purge air from a kickspace heater? Does it have a bleed screw on it somewhere? It's not clear from the literature, and I haven't ordered the heater yet....
Finally, I was wondering what method pros use for balancing direct return systems...If I measure the delta T across a given radiator and it's less than 20deg, I assume that means that it has sufficient flow?
Thanks in advance for any help!
Nathan