Tony,
I often think this site could become a 444 Marlin web site. The 444 is, our hero, Marshall Stanton's pet cartridge. I'm sure I'll buckle under the pressure and pick up an Outfitter before too long. There's plenty of data on loading and all sorts of other great information on this round already posted here. You can use the SEARCH feature, typing in 444 Marlin, and enjoy.
As far as factory ammo is concerned I'll plead ignorance. I haven't bought factory rifle ammo in quite some time. You can always load up something more accurate, cheaper, or both on your own.
Enjoy your new rifle.