Selected track listener (and track finder) with Reaction

Good morning,
This is my first trial with reaction so thank your for your patience.

I would like to implement a simple Reaction in order to get the selected track number and send a MIDI CC Message (on a given channel and CC #) back to the controller.

Please note that this reaction should be triggered when the selected track # changes but also during the script initialization.

Also I would like to memorize this number in a variable (eg. m1) for later use.

Thanks in advance for your support. Have a Nice day !

PS: I have another but similar request to scan tracks during a script intilialization, find a track with a given name (eg. “MPK”), put the track # in a variable (eg.m2) for later reuse within the script (and also send a MIDI message with this track #).
Thanks again for your help.