It is the same cartridge, you can run a 30/06 in a 308 die and make a 308 after you trim the neck. Same for 270, 243, 25/06, all based on 30/06 brass. Some other wildcats as well.
Yep. 260 Rem, 280 Rem, 7mm/08 etc.
All the same cartridge head/rim specs. 308 can go into a shorter action.