Welcome to the forum.
As you are new to muzzleloading you will see some terms that might be new to you.
Jag is one of them, often not used by people who are familiar with modern guns.
It is basically a grooved brass plug that screws onto the end of a cleaning rod.
It comes in various sizes described by caliber.
To use it, a clean wet, damp, dry or oily patch is placed on it for swabbing the bore.
You can do 90+% of all of the cleaning you will ever need to do if you have one of these.
Here's a link to a good place to buy them.
https://www.trackofthewolf.com/List/Item.aspx/580/1
As for the rod, while a range rod is great, a steel cleaning rod made for modern guns will also work if you can find one long enough to run the jag all the way down to the face of the breech plug.
Be sure to get a rod with a #10-32 thread in it.
The #8-32 threaded rods are not stout enough to last.
You can use any cleaning patch made for a modern .45 caliber gun. It is large enough for your .50 caliber barrel.
For normal cleaning on a muzzleloader a little plain water with a touch of dish washing soap is all you will need.
To clean your guns barrel, any cleaning fluid will work.
If you use soap and water, don't forget to dry the bore with clean patches and then run a oily patch down it. Your worst enemy is rust so lightly oiling the bore is very important.
Have fun and keep us informed about your guns progress. Also, remember, you can ask any question you want to ask here on the forum.
We've got LOTS of answers to help you.