Gamers Nexus reports 44W at idle with the G4560 which is already more than the G5400T’s MAX TDP of 35W, so it’s a pretty significant difference.

Assuming the RAM and other components are similar, I’d go with the G5400T system.

Unfortunately no, which can make it a pain to figure out. You’d have to research the CPU itself.

The thing that matters more than the TDP is how much power they draw at idle. It’ll likely be idling or turned off more than it will be on. And even when on, it probably wont be hitting its max TDP just playing some media unless you’re transcoding to 4k or something.