H4895, IMR4895, Varget, and IMR4064 are popular powders for the Garand. There are others and the burn rate is around those listed. Get outside the appropriate list of powders and you risk damaging your rifle.
Generally, folks say stay with bullets between 150 and 175 but lots of folks use bullets as light as 110 grains and over 200 hundred grains. Caution is the word here but it is possible. I don't see any need to go heavier than 175 or so grains but what ever.
Commercial hunting ammunition should not be used without a gas relief plug like the Shuster. I forget the name of the other relief gas plug at the moment. Hornady and Federal make Garadn specific ammunition.
The current Hornady manual has a Garand loading section. Not the be all to end all, but a good basis for beginnings. There is a NRA publication from the 80s or so with some good loading information. The CMP forum is a good source of loading information or loading sources.
I load mostly 150 grain bullets over H4895 but have also used IMR4895. I have dabbled with 110 grain spire points and plan to do some more. For 100-200 yards, they are great and the recoil is a bit less than the 150 grainers. Flat base bullets may give better accuracy than boat tails at the shorter ranges.
Full length sizing is a must. Some folks use a RCBS Precision Mic or a bump gauge to set the shoulder back .003-.005 inches. Make sure the primer is seated properly, slightly below the level of the case base.
Slam fires are not really an issue if you follow prudent reloading practices. Get sloppy and you will have problems. I have had one "slam fire" in 10 years of Garand loading and I think it was more of an issue with "milking" the trigger than a slam fire.
No crimp is necessary with Garand reloads. Neck tension holds the bullet in place. Crimps will not correct poor neck tension.
I can easily keep my shots in the black of MR-31 (100 yard reduced range prone target) shooting slow fire from the prone position at 100 yards. It is better than my groups with HXP surplus. Lots of folks can do better, but I am happy ad my eyes are aging.
Hope this helps. Enjoy your new Garand. I enjoy mine.