If the $30 isn't an issue, I would reccommend getting the DB retracts. I installed a set a Hobbico retracts in the GP Lear Jet a few years ago. They were pretty hard to get adjusted correctly, and I didn't think they would hold up to a hard landing. If money really isn't an issue, I would definitely look into pneumatic. I wound up replacing the Hobbico mechanicals with Robart pneumatics about a year ago, and as long as you remember to keep the air tank filled, they are very reliable.
As for the wheel well, I usually rubber-band a few we pieces of balsa around a pop can and let them dry. When you pull them off, glue a few together to make a complete circle. I like to glue them in the wing and sand them flush with the ribs before I sheet the bottom. Then just use any fuel proof paint or thinned epoxy to protect them. Hope it helps.

Ty