I'm unsure how to set up the inventory and I don't understand the combat, controls, plus the first dungeon seems to very hard with monsters able to 1 hit kill in some instances. I don't understand how to level up characters. I'd really appreciate some advice so I can play and enjoy the game.

Thanks in advance.

I recently completed the game. So I can help you if you have any problems. The combat is kind of difficult until you get to understand it. As a begginer I would recommend that you play as pipiro (The girl) which can shoot magic from far.Also you should go to a dungeon after meeting the required level . Even one level below the dungeon requierement and the enemies could kill you easily.Also dont eat every food you get try and save them in batches of 10 and then upgrade them at the bar for a better food that gives you even more exp. Also don't forget to purchase some armor and healing potions.

If you're just starting out, the best thing you can do is buy and equip the power stone from the shop. It may not look like much when you look at it purely from the stats (most things don't), but you will make combat much more manageable. Without it you are essentially walking into combat unarmed.