Can members of Congress be removed from office through the impeachment process?

Answer 1

Technically, I suppose they could, but there wouldn't be much point. Impeachment would require the involvement of both houses, when according to Article I, Section 5, each house has the authority to expel one of its own by a two-thirds vote:

"Each House may determine the Rules of its Proceedings, punish its Members for disorderly Behaviour, and, with the Concurrence of two thirds, expel a Member."

Answer 2

Maybe.

Article II Section 4. "The President, Vice President and all civil officers of the United States, shall be removed from office on impeachment for, and conviction of, treason, bribery, or other high crimes and misdemeanors."

It depends on whether Congressfolk count as "civil officers". Probably not, since that term is generally defined elsewhere to mean individuals appointed, rather than elected.

{EDIT} Kudos to Chris.S (below) for the better answer.

Answer 3

Probably requires a recall election or they have to do something which sufficiently violates the ethics of Congress. That last one is pretty hard to do these days, though.

Answer 4

Maybe.