Not a .280 guy but I see a fellow in need
I'm sure that each type of action has it's followers and naysayers but for my .02 I'd recommend a push feed action. My reasoning is that most CRF actions like to be loaded from the magazine and have troubles or refuse to grab on to cartridges that are loaded one at a time and not pushed into the magazine. This isn't the case with all CRF actions and really is not that big of a deal.
Some like the fact that with a CRF you can change how hard your empty brass flings by how hard you pull the bolt back. I personally feel that the plunger style spits them out just fine. again just my opinion.
I know that Savage went to CRF on their ultra mag chamberings so there must be something to having CRF for larger brass (I built a .300 RUM on a Stevens and haven't had a problem with the push feed). Shouldn't be a problem for the .280 anyway.
Since the .280AI would have the same case lenght as the .280 I wouldn't think there would be anything special to it. My advice would be to check out some loads that guys are using for C.O.A.L. and then go to manufacturers sites to check out magazine size. I would thing that most standard and any magnum magazine boxes would be fine.
Do you have a specific budget for this rifle? If so I would not count out a Savage or Stevens action. They might not be as pretty but they work fine, have tons of after-market parts and you can use the money you save to upgrade optics or stock. Plus you can change the barrel yourself without a lathe.
Hope that gets the ball rolling for ya?