Looks like a very nicely sportered Krag.  It appears to be cutdown with a 1903A3 front sight and a Redfield 102 no-tap rear sight.  It should be a pretty good shooter, and quite accurate too! 

As for ammo... yes, Remington and Winchester factory ammo is fine.  There is other factory ammo available too, from companies like Bitterroot.  Check with web sites like Cheaper Than Dirt... the ammo will be less expensive than buying at a sporting good store.  A word of advice...  Save your brass!!!  You may not want to reload now, but with the price of 30-40 ammo as high as it is, it will definitely save you money in the long run.

Welcome to the wonderful world of Krags!
Paul