It doesn't look like that NitroPlanes has the manuals up on their site, so the answers are going to be a guess.

Does the instructions show a wing tube?? If not, one is not needed would be my guess. It standard to holes in the ribs to cut down on the weight as well as providing a path to run servo wires through. I would follow the instructions and do no more, or no less that instructed.

When gluing two wing halves together, there is usually a dihedral brace of some sort though near the main spar. Those kits that use a dowel to provide alignment of the trailing edge, should call it out in the instructions. The dowel only provides alignment. The dihedral brace provides strength to the wing. If the kit didn't provide either a diherral brace or a tube, I would be concerned

These are questions I would send directly to NitroPlanes. Without having the instructions avaiable, and without having built one, I can only address what I have run into with other kits. Hopefuly someone who has built one will jump in. but even if the do, contact Nitroplanes.

Don