A: For type M copper tube, ASTM B88 and NSF/ANSI Standard 61 – Annex G require a minimum copper content of 99.9% and phosphorus content between .015 - .040%.
A: 100% solid pure hard copper.
A: copper throughout
A: No. Its a straight pipe with no threading.
A: No threads. It's made to solder into copper fittings.
A: No, no threads. You would “sweat” the connection with silver solder