Well Hello and welcome.
the cleaning of a muzzleloader is a personal choice. Pyrodex is not water soluable so if you want to use the water / moose milk method use a good paste lube on your patches, or use real black.
As to loading your new beast, forget pellets!! loose powder is best in side locks. I assume this is a percussion gun (not a flintlock) number 11 caps are most likely what is needed, but since this is a used gun ask the previous owner what size caps to use, it is easy to convert them to musket cap, or even small rifle primers (I do not recommend this)
80 grain load of pyrodex is too vague, does he mean RS, Select, or P? All three have different pressure and velocity characteristics. All of these are different from Goex characteristics, which are also different from elephant powder (add that 3F and 2F are also different from each other and just add to the differences between the brands)
85 grains of Goex 2F is my hunting load in my Traditions Hawken.
Patch thickness, patch lube, and ball diameter also affect the accuracy of the load, as well as follow up shots. Ball diameter can be .490, or .495, patch thickness can run from .008" to .020" or more in extreme cases
The use of conical bullets depends on the twist rate of the barrels rifling. 1:48 twist up to 1:20 twist rates will shoot them, 1:60 down to 1:80 will not. Rifling depth also affects the use of conicals, a shallow rifling will do well with them, deep rifling needs a patched round ball.
There are two books I would recommend for you. Get them both, read them, and learn your new rifle with the information in each.
Lyman's Blackpowder Handbook and Loading manual written by Sam Fadala, and The Complete Black Powder Handbook, also written by Sam Fadala. Combined they will explain all you need to know. Max loads will be listed in the owners manual, if one does not come with the gun, call, write, or e-mail Cabela's and they will send you one. it will list the recommended cleaning and loading procedures.
Good luck and have fun it, but do not try to make it into something it is not