This would seem to mean that surely all members of the Cabinet would be removed, but what other offices would be purged?
I'm also questioning what happens if the president resigns before the impeachment is completed? Can the impeachment process be completed? Once started, is Congress compelled to complete the impeachment, considering that the results extend beyond the president? Is there some way that the process can be thwarted so that an impeachable president can remain in power, by proxy?

Power to the people, get him out! His act of treason was seen by the entire world on TV.

Attack your "representatives" with emails, texts, calls and insist they act! Put their contact info into your phone/computer so it is easy to do!

I want to see Trump, Pence, and just about every other Republican out of office as much as or more than anybody else, but I don't think the collusion (an imprecise legal term) qualifies as treason. If memory serves, for an act to qualify as treason the US must be at war with the enemy; since we're not in a declared war with Russia, it's not treason. Now, if we can impeach them for ... well, anything else, that would be great. Maybe after midterms when the Democrats have a majority in the House so that the House speaker becomes president. Of course, if the Senate is split then the Vice President will be ... McDonnell? Ugh.