1. Suit it to the rank of the class, not your physical level. Stats on gear above your current rank scale down. On armor it isn't too bad, so equipping gear a few ranks higher is ok. On weapons and tools it is harsher, so it's typically better to not equip a weapon or tool that is of a higher rank at all. Keep in mind that equipment above your current rank will degrade much faster.

2. You can do 8 regional leves (battlecraft or fieldcraft) every cycle, which lasts 36 hours and (I think) resets at either 12 noon or 12 midnight GMT. After that, do quests, try crafting, or even go explore. After the reset, you can exchange your old leves, completed or not, for bonuses on your next set. When you go to exchange leves, you'll see some stars next to your old leves. A leve gets 1 star for being from a different city than the leve you're accepting. A leve gets another star for having a different picture. The number of stars on the (up to 4) leves you turn in determines the bonus in rewards on that leve. These can be significant: exchanging with 8 stars doubles the leve reward. You can use this to quickly obtain many guild marks for your fighting classes.

I'd be happy to help, but I'm on Wutai. Good luck!