First off if you are going to use 777 then plan on cleaning the barrel every shot it is necessary if you get what we call crud ring and the majority do. Even if you did not get much crud ring it is necessary to at least swab every shot. Pellets are not only overly expensive they do not let you tune your gun for max accuracy, I suggest loose is best.
I have used Win. 209 for reloading and STS Rem. for reloading I like both and it seems to me like the differance between them is minimal.The best cleaning fluid in my humble opinion is a 50/50 mix of windshield washer and alcohol, this is good for black and all subs except the best one which is Blackhorn 209, Blackhorn has what some people consider one draw back, it is almost as expensive per shot [if you don't find a deal] as 777 pellets.
Accessories, Ramrod that comes with the gun + the T handle short starter that you can screw into the ramrod to make a temporary range rod the jags that come with the gun to start and cleaning patches [ I buy flannel material for sheets at Walmart and make my own. you also will want the little two pronged patch puller so you don't have to go to the trouble of pulling the breach plug if you loose a patch down the bore [it happens to all of us]
While this will get you by to start with there are a few things like a range rod and some sabots of different thickness some extra jags and a shooting box to carry your stuff in some targets that you like but a lot of this can wait till you get started and learn to pick out the class and quality of accessories you want. How much shooting you end up doing will affect that to. Lee