This is a massive collection of reports, correspondence, etc. It's a confusing resource to navigate, consisting of something like 70 volumes, but it is an absolute treasure trove. Every time I go to research a specific subject, I end up getting sidetracked, reading fascinating documents that have nothing to do with the subject I'm researching. It's addictive.
Regarding the Arkansas regiments in U.S. service -- they were armed, equipped, clothed and paid just like any other volunteer regiments.