U.S. Attorneys' Terms and Historical Firings

VC had a comment thread with a lot of contradictory opinions on historic US Attorney firings. Wikipedia says

The U.S. Attorney is appointed by the President of the United States[7] for a term of four years,[8] with appointments subject to confirmation by the Senate. A U.S. Attorney shall continue in office, beyond the appointed term, until a successor is appointed and qualified.[9] By law, each United States attorney is subject to removal by the President.[10]

Thus, the following are all true:

(1) U. S. attorneys can be replaced in the first year of each presidential term without being fired, as their terms expire, yet they aren't all replaced the same day because they serve till a new person is appointed.

(2) When President CLinton fired all of the US Attorneys in January 2001, that was a true firing, because he did not end their tenure simply by appointing replacements. Firing them all was within his authority, however, even if unprecedented in recent times.

(3) When Bush fired 12 U.S. attorneys, that was a true firing, but was within his authority, even if it was unprecedented in recent times to fire more than one U.S. attorney appointed by someone of the same party at the same time.

(4) When Bush replaced US attorneys at the end of his first term, that was not a firing, but simply non-renewing.