For gear you ideally want a weapon close to your level(weapon matters the most), armor within 10(make sure its the kind designed for your class), and jewelry... jewelry barely matters before level 50, so jewelry with the right stats(dex) for your class. Vendor gear is fine if you dont have dungeon drops to use. Once youve done some solo fights to get back into the groove it wouldnt hurt to try one or two of the easier instances first before jumping directly into the next one the story will send you to. You could do a couple guildhests, or maybe one of the dungeons around level 30. Then once youre comfortable jump right back in where you left off. Welcome back, and good luck!