I'm not sure if this is answered anywhere, but for Item hunter, do you have to do all 5 of his quests everyday or can I take it at an easy one quest a day without losing my streak?

No, you can choose how many (if any) you want to do. You only lose your streak when you fail one of his quests. It can be useful to deliberately fail his quests and lose your streak so you can start over, as his quests end up costing /a lot/ after a certain point, so you'll lose money on them.