The rifle is already safety checked, but CMP doesn't warrant that for liability reasons.
Scott Duff's book is a good start, Jerry Kuhnhausen's shop manual is fantastically detailed.
Get a good Turner Saddlery leather sling. A good sling, properly employed, will dramatically improve your shooting.
Get either a good one piece coated rod, such as a Dewey, or an OTIS pull through kit. Save that muzzle from cleaning wear.
Get a good supply of clips. There are places out there that sell them by the hundreds. By at least that many. You may not wear them out that fast, but it's nice to have a good supply.
M2 ball ammo is getting scarce out there, but Federal American Eagle brand ammo is supposed to be OK, so is PMC's 150 grain M2 ammo (designed to closely mimick M2 ball). Standard .30-06 hunting type ammo burns too slow and generates too aggressive a pressure curve for the M1's gas system (especially the carefully bent op rod) While occasional feeding with hunting ammo won't kill the rifle, It would be prudent perhaps, to buy one of McCann's adjustable gas plugs. It is basically a standard gas plug, drilled and tapped to take allen headed screws in place of the poppet valve. These screws are themselves drilled out to release excess gas pressure. Find the right screw by firing. The screw that drops the empties between about 1 and 3 o'clock is the right one. Costs about 35.00 direct from McCann's probably a bit more from Brownell's.
Spare parts. You'll probably want to get a complete set of small spares for the M1. Many of these rifles are over 60 years old now, and while they have been through arsenal refurb, some have been heavily used after that. Firing pins, ejectors and ekector springs, Extractos and extractor springs, followers, follower rods, and the various pins and what not are all good investments. A newer condition trigger guard may also be a good idea, this can significantly tighten up lock up to the stock. You'll know more when you get your rifle.