i’ll let others comment on other points but wanted to clarify these two:
yes, it will power devices connected to it, which means you can use it to connect grids to oder versions of teletype that might not be able to provide enough power themselves.
of course, this means you need to make sure 2>1 itself gets enough power, since a grid can draw up to 600mA when fully lit. if you power it from eurorack, you have to make sure that your +5V rail has at least 600mA available, taking all your other modules that use +5 into account.
it’s possible teletype will act weird if you plug arc into it. i just tried it and it was fine, but again, since it doesn’t expect it there is a non zero chance something funny might happen that will require teletype to be power cycled. i doubt anything will get damaged though.