Because we're living through the collapse of the American empire where the majority of politicians are blatantly corrupt and no longer care about hiding it.
They weren't president when they did it, so no. But the new president could just pardon himself if the GOP approved of the assassination, since the 6 SCROTUS's would say it's legal to do so.
Depends on whether or not the GOP wanted it to happen. If they did, the 6 SCROTUS's will declare it an official act. And hey, if they don't like the new president, the new Vice President can do the same thing until they get one they like!
It's fucking ridiculous, but completely within the law as the SCOTUS has defined it.
To be fair they should just work most of their time from home on zoom and stay in their own states so they can be closer to their constituents. Going to DC is great and necessary but with modern technology they should be way closer to their constituents than they are. That's just my opinion though and what do I know.
It's actually even simpler. The whole building has wired feeds of the floor. So you can work from your office in the building or nearby, watch everything, and only come to the floor to vote.
I agree with the idea, but I highly doubt this is why they are not there in practice. I could be wrong as this is just purely speculative on my part, but I don't have a lot of faith in most US politicians.