first of all, there is no really list for Items i know.. just stuff like this: https://dragonquest.fandom.com/wiki/Category:Dragon_Quest_X_healing_items
you can just, press X on ya Switch controller when you are in the item menu, you will see the icon of each item!
spells for ya class work a little bit different, the last skill tree is ya Class skill tree, the others are just weapon skilltrees.
when you change a class, you get all the passives, and some active skills in the other class when you skill the class tree..
you cant really bad skill or something like that, just take a weapon that you like and give it a shot!
and level the other jobs as well, so you get nice passive buffs and stuff!
sry for my bad englisch... but i hope it helped!