It's been a while since I've came across this question. Like in most games, the items that have a "?" are unidentified items. You need to take them to a vendor to get them identified. It costs 100zeni to do that. You should wait until you start finding them off mobs that are in the mid 20s before you identify them. The lower the level, then less zeni you will get back for vendoring them. If you wait until the mid 20s, then the items will sell for a 100zeni or more.
As for bags, you can purchase them from merchants also, or look through the AH. Last I checked, you can get the large capsule bags for 97k zeni. They used to be like 330k zeni
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