1. Ask your local authorities. Some states like NJ may have unreasonable gun laws. Normally it is not a problem since it is an antique gun.

2. Civil war guns do fine hanging on the wall supported by gun racks if the area is a living area with humidity and heat controlled. Don't hang over a fire place or in direct heat and you should be ok. Dust it off occasionally. Without seening the condition of the gun it is hard to tell what stock or metal preservation may be necessary to keep the weapon in good shape. Do not clean the exterior of the gun or take it apart until someone knowledable about antique guns looks at it. Over cleaning can ruin the value. If it has a ramrod, hold the ramrod against the barrel and determine where the ramrod should be if the tulip end is even with the end of the barrel. Now drop the little end of the ramrod into the bore (don't force it). if you have two or three inches of ramrod sticking out at the top of the barrel, it may be loaded or have a barrel full of dust and dirt. Have someone familiar with antique arms take a look at it. You should know that the normal gun shop owner may not have the necessary knowledge of muzzle loading, antique arms to make these decisions.

If you still want a case, go to a furniture maker and have one made.

Are there any markings on the gun?

My .02 worth.