Welcome,
I am new here as well. I have a couple Montana Longbows 50# and 60#, I love the bows. I guess, like you that is what I started with so I judge all other bows compared to the Montana.
My 50# shoots Gold Tip 5575 with 250 grains up front like darts. I like the carbons and wood arrows over aluminum but this is a personal choice. You can make a lot of different arrows work for you, just start off with different weight field points, they're way cheaper to play with than a bunch of different size arrows.
I would recommend replacing the factory grip, rest and side plate right away so you do not have to tune the bow twice. The factory grip, rest and side plate will not last long with much shooting. I would also recommend a good flemish twist string, a good string will make a big difference on your bows performance.
I wish that I would have seeked out advice when I started. I think you have picked a great place for advice. Enjoy your new bow.