I'm the lawfag that posted about that convo. Just starting to dig on this today.
Here are two starting points. Legis law ain't my thing, we must have legis-law-fag anons here, so hoping someone else can step up to help.
LIbrary of Congress – Impeachment
https://www.loc.gov/law/find/impeachment.php
Hearings in the House of Representatives: A Guide for Preparation and Procedure
Congressional Research Service (CRS)
NOTE: This is dated 2006, but is a useful starting point.
https://archives-democrats-rules.house.gov/CRS_Rpt/RL30539.pdf