Unless I'm mistaken, the only extra- or supermajority vote mentioned is for ratifying treaties. Two thirds required in that case. The filibuster rule has been changed in regard to parliamentary delaying tactics for legislation in the past.
Impeachment also. For some reason I thought there was language as to legislative matters...but you are more than likely correct. I'll read up on it again later.
Conviction for impeachment (2/3rd of members present); override presidential veto (2/3rd of HOuse, 2/3rds of Senate);concur with treaties made by the President (2/3rd of Senators present); Constitutional amendments (2/3rds of both houses).
Yep...you are correct. I couldn't find anything on legislation in Article I. Supermajority is only discussed in Article II.
Don't know where I got that impression.
From 1789 to 1806, a simple majority vote of Senators would move the question. From 1806 to 1917, there was no method to force the vote over the objection of a single Senator. From 1917 to sometime in the 1970's, cloture required 2/3rds of members present, and was changed to its present 2/5ths of elected Senators.
Which makes another argument. The hurdle for approving nominees is better what the Constitution implies (simple majority), not what the Senate says it is "today," which hurdle may change "tomorrow."