I have an older set of Descent, and yesterday I played with some people that have played recently and they told me my monster cards are out of date. Is there a new set of cards for the game? If so, how do I get them? Also, is there an errata and/or FAQ on this website? Thanks

FAQ and errata are on the Descent Support Page.

Updated versions of Beastmen, Skeletons, the Bow, the Bow of Bone, the Golden Armor, and the Dragon Scale Mail (maybe a couple others) are included in the Well of Darkness expansion, and in more recent printings of the base game. The changes are also listed in the FAQ.

Beastmen got straight +damage instead of their piercing, Skeletons got piercing added, the Bow got Pierce 1 but still sucks, I think the other changes are all fairly minor. Though people keep getting confused that the revised version of the Dragon Scale Mail provides immunity to a status effect that isn't introduced until Well of Darkness.

Perfect. Thanks a lot!