Yeah Kbop, #2 would be more fun but the lawyers in the Senate will prevail.
Looking at Article I, Section 3 - Clause 6 and 7 of the US Constitution, the Senates sole role is to "try" so in essence the Senators are jurors. It would be unheard of in a court case for the presiding judge to have the jurors ask questions of witnesses let alone summon them to do so.
I suspect, Chief Justice Roberts will throw out the Obstruction of Congress Article. As I have already mentioned, the SCOTUS has taken on the Executive Privilege question concerning Trump's tax returns.
Last, if one or two of the articles wins and moves onto the Senate; this event will not become rare but common in the history of the United States and the Executive Branch.