Hey North Nick,
I recently got a 209x50 barrel for my encore as well. I'm no expert by any means! So take what I'm saying worth a grain of salt. For me the goal was to make muzzleloading simple so that I could hunt a little more each year, sound familiar? Anyway, I'm not a blackpowder expert by any stretch of the imagination, but here's what I found out.
As far as what powder type, for me it was simple. They make powder pellets to idiot proof it for guys like me, so that's what I'll use. They say you can put 150gr of them in the barrel if you really want to (i have), but I only use two 50gr pellets (100gr total). That should be plenty.
As far as bullet type goes, I've tried several different sabots, and they're all a pain in the butt to seat the same and even force down the barrel. So I tried the PowerBelt bullets 295gr hollowpoints. They grouped well at 100 yards and I was done, and happy.
I've used a couple different 209 primers, and don't see any real difference between them. Use what ever you want there.
At the range I would brush the barrel out between shots, and I'm only talking about a couple brushes down the barrel then a dry bore mop (those giant q-tips that thread onto a cleaning rod). I'd do a couple of those in between shots, just to keep the gun shooting. I have never run oiled patches down the barrel because when I get home I clean the heck out the thing. Maybe I should be but I don't know.
I highly recommend buying an e-zee tip extracor just to make life easier on yourself. They're cheap and they work. Pop out the breach plug and I run a 20 gauge bore snake through mine a couple times after already cleaning it the regular way.
I'm sorry this is kind of wordy but I hope this helps!