simple version.
.45, .50, .54, and .58 are the most popular calibers, but .50 definitely above the rest.
Sidelock hammer, flintlock, and in-line are the three styles. In-line being the most popular for new gun purchases.
WA requires and exposed nipple/cap, so not all in-lines on the market are legal.
most common scenario is powder between 60-150 grains down the muzzle. Bullet down the muzzle, making sure it is tight to the powder. apply #11 cap or musket cap and sight and fire. reload or clean as next step.
several variations on powder available, but there are few commen ones that show up most frequently. 777, Goex, and a few others
Several different bullet combinations. saboted lead, saboted copper, round ball, maxi ball and others.
Best way to learn more is to do what you are doing and ask questions. Go talk to as many people as you can and maybe someone from the forum will let you shoot theres and go through the process with you. I learned some things the hardway, seized breech plug, stuck ramrod, broken sights, lost peep, wet powder, wet cap, etc. But that is the nature of hunting with a little bit more primitive weapon than modern firearm. Fun thought!