I don't think I can answer any of those questions, sorry.
One thing I want to bring to your attention. I believe you said your main purpose is to receive train locations from various sensors and send out TMCC speed commands to the base unit to adjust their speed. In my opinion Speed commands are the hardest of all TMCC commands to get working and the logic around them. The TMCC spec gives you two options for speed commands, Relative and Absolute. Not all engines respond to both. Some engines will only respond to one or the other. You may have to experiment. My software gives users both options, but I believe in your case, since you want it all automated, you might also have to store which speed method each engine needs in your engine array.
