If Trump is impeached and convicted under the current House indictment, could he still be tried in federal or DC courts on related felony charges? I am thinking of sedition, inciting a riot, or some such.It would be great to bar him from office, but he really deserves hard prison time.
Yes, impeachment does not create legal jeopardy. Several judges have been impeached and removed as well as convicted of federal crimes for the same conduct.
Impeachment and removal is not a criminal procedure; it is conducted by the legislature (although the Senate trial for removal is overseen by the Chief Justice of the Supreme Court) and is essentially an administrative action, albeit the only one that can permanently remove a sitting President. Any acts he takes in the Office of the President may or may not be protected by executive privilege although doing something such as, say, interfering with the conduct of an election involving himself is clearly not even an ex officio function of office; ditto for fomenting insurrection or any other conduct which could not reasonably be construed to be acting within the recognized duties and responsibilities of the office.
Stranger
Yes. They were concerned enough about making sure that was still possible that they put it in the text of the Constitution:
Judgment in Cases of Impeachment shall not extend further than to removal from Office, and disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States: but the Party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.