“The Founders intended the representative of the people and states, in Congress, to be in ultimate control of the government.”
The impeachment process is intended to determine whether or not the impeached government officer may continue in a government office with its attendant powers and authority, but it is not intended to provide criminal trial and punishment for criminal felonies beyond the punishment of removal from office.
True.
Should note that even if legally justified, pursuing an impeached or term-expires president with criminal charges would have serious negative long-term consequences for the country. Might very well not be worth it except in the most extreme circumstances.