Yes, they are header tanks. One for each wing tank. These prevent getting air pockets in the fuel system from fuel sloshing in the main tanks. The reason for two are because you can swith tanks with the fuel valve. Search this site, I'm sure there is much discussion on this and other fuel related topics. Happy building!
Welcome to the Magnum insanity!!! 1. My wings where already set up when I bought my kit, but I did double check everything before I covered them, and the previous builder did a great job. The manual explains in detail how to set up the wings, let me know if you need a copy. There is only one adjustment on the lift strut on the left side only. Others will most likely have more experience with this subject than me.
2. My wings where also built with tip tanks and I eliminated them by adding the 3 false ribs, no big deal. You can find it in this post back a few months. No need for bottom false ribs either. 3. Not sure what you mean about wing tips, are you talking about tip tanks? If so, I chose not to use them because my bladder only flies for 3 hours at a time ;)) 4. Check out the gear Ron and I used before going Grove, this is also documented on this forum in detail. Grove is good too, but our set up doesnt have near the recoil that a Grove will. IMO Blue Skies, Barry