For me at least, there isn’t much distinction. There may be many reasons why someone isn’t doing their job, but ultimately he wasn’t.
Absolutely. I don’t think “temporary” removal via the 25th amendment would have obviated the need for impeachment. The 25th amendment was the “in case of emergency” button that would have let Pence do a hopefully better job of managing the crisis. Impeachment and removal is the slower (but still should have happened already) legal repercussion for inciting an insurrection.