I most heartily concur with WW.
Make sure it's unloaded, clean out the bore with Hoppe's #9, dry it with patches, and give the bore a light coat of a good gun oil (again, I like Hoppe's), but I've heard good things about RemOil too.. Put a little oil on an old tee shirt, and lightly coat the metal parts, put a little oil in the lock parts.....and leave it alone.
As for the rifle being something special....well, there were a lot of 1860's made. Some variations and later modifications being fairly valuable......far too many to list here.....
I'd suggest that you go to your local library and take out a copy of "Flayderman's Guide To Antique American Firearms And Their Values", which is sort of the Bible on the subject.
Or, if you're enough of a GunNut to want to buy a copy (a good reference book to have), here you go:
Amazon's running a good deal on it right now, $24.12.
Barnes & Noble also has it for a bit more: