These are true mil-spec 308 firing pins. They do not work with the 6.5/6mm Creedmoor bolts.
Yes, it will.
The V Seven Titanium Firing Pin is compatible with 5.56. Model MPN:FIREPIN-TI 556 is specifically designed for AR15's and the 5.56 Cartridge.
No it will not work with 5.56.
The V Seven Titanium Firing Pin is constructed from grade 5 ELI Titanium, while Mil-spec firing pins are made from AISI 8740 steel and chrome plated. Titanium is as strong as steel but 45% lighter. And if the US Military is using AISI 8740 steel firing pins, then this will work just fine with full auto/Binary fire.