One thing to add about optimal level. While I was leveling my ARC I found a few pieces of gear that were optimal level 25. After I equipped and looked at all of the minus to stats it was still better than the level 1 stuff I started with. I was around level 15 when i started using the level 25 gear. Once I hit level 20 the item went from showing orange text in the optimal level spot to showing yellow text, and the minuses went away. So based on that observation it's probably OK to use gear several levels higher than you, as long as the minuses are not leaving you with lesser stats of course. Also the extra stats higher level gear has such as +10 HP or +10 Attack Power will not benefit you until the item is at least yellow to you.