Hi,
I'm not sure how to read the "Radio Switching" and "In-Cockpit DCS PTT" columns, so I will confirm how it works IRL:
The pilot has a "selector" on his throttle. This selector has 3 position, and is spring-loaded so that with no pilot action it's on the center (= neutral) position.
When the pilot wants to use a radio, he presses the selector on the side he want (one side = one radio), that selects the radio to use + acts as a PTT, so the pilot maintains his finger on the selector as long as he speaks.
Also regarding the M-2000C's TRT ERA 7000 (V/UHF) (=radio 2 in your table), please note that this radio also has the capability to listen on both the current frequency/channel PLUS the guard channed; this is done by placing the rotary on "Pal+G" (means "Main + Guard") instead of "Pal" ("Main") only.
++
Az'