Greetings from Georgia !
As an avid long range shooter, I believe that I may have some ideas that will be of some help. I believe that if you plan on hitting an object at 500 yards or beyond, the first thing you should consider is finding a range where you can shoot that far. I am lucky enough to have a 500 yard range at my house and we use it quite often. As far as equipment, that is up to the individaul, but without a LOT of practice at long range the full potential of any gun will never be reached.
One of the things that we have found through the years is that very few people can "really" hit an 8 inch steel plate from more than 300 yards. Sure an occasional ring will happen, but that is not adequate to rely on in the field. Right now I have my bench set up for 300 yards and have been wearing it out, with everything from the tiny ,17 HMR up to the mighty 45/70. Beyond the 300 yard mark is where all things must be working together well, both human and hardware. After tuning the rifle to find the most accurate round, start airing it out to see what happens !!
I have found that one of the most useful tools I have for shooting well is a GOOD rangefinder. Once you have used it a lot, ranging by eye comes easier, but a misjudgement of a few yards at long range can mean a miss. Good luck and God Bless.
Dave