Marc,
Getting a C&R is very simple and straight forward, just takes some time.
In regards to your black powder rifle. Federally, at least black powder and anything older than 1898 can be sent to and owned by an individual. Unfourtunatly every state has their own quirks and modifications of the laws. I know here in NY for example, we are able to own even black powder pistols without a permit, but you need a permit to fire it or to have all components for firing it togther with the gun in one place.
Back to the C&R license. It is well worth it. It costs $30 and is good for 3 years. You can go onto the ATF website and request the documents for application be sent to you. All that is required is the application. No finger print cards are required for C&R. You just fill out the two copies of the application, one for ATF and one for your local police chief. You send ATF's in with the payment and the police's direct to them for their records.
Within 60 days you will get your license providing that you pass the background check with ATF.
The fee is supposably refundable if you do not pass, but they do cash the check once it is received.
The C&R license allows you to purchase and receive directly, state to state and on-line, any firearm that is over 50 years old or on the ATF list of C&R elegable guns. Obviously with some models that were made for very long production runs, you may have to look up the serial numbers to prove date of manufacture. But with other guns, they are clearly over 50 years old.
So obviously the benefit is that if you are a collector, once you pay for more than on FFL transfer, you have paid for the C&R. And if you intend on buying even 2 guns in that 3 year period, it is well worth getting.