You can use up to 150 gr. of black, pyrodex or 777 in that rifle, of course every rifle is an individual and one may like max charges while another does not. I think the greatest advantage the pellets enjoy is convenience (plus they're a lot more expensive than loose powder so you'll be helping finance someones next african safari if that's important to you. The greatest advantage for loose powder is flexibility to work up the perfect load for a given rifle and a given bullet. This may be 110 rather than 100 or 150 gr. Don't discount this.

777 in my experience, fouls the same as or a bit less than pyrodex. If you're using sabots (imo, an answer in search of a question) the plastic fouling may require cleaning before further loading but if you shoot lead conical or black belt type bullets cleaning between shots isn't usually required. In fact, that's one of the prime requirements in my mind of a hunting load. If I need to swab or clean the bore in order to maintain accuracy or facilitate loading it ain't a hunting load. Those antics belong to the target range.

As far as a good informative black powder site on the web, I haven't found it yet. As a starter, you might pick up a copy of Sam Fadala's Complete Blackpowder Handbook. Good shooting!