Congrats on your decisive new purchase and, with five total hulls, your sacred ascent into boatsluttery.
White gel coat is the best color to hide oxidation since the oxidation is also white. I'd wash the outside with a good scrub brush. If there is oxidation you could try polishing compounds, but I've never found them to be worth the time and hard manual effort. Just apply, and after five minutes wipe off, a coat of Penetrol, which takes about 10 minutes total for an entire canoe hull. That will make the oxidation optically, though not physically, disappear. (Oxidation causes micropits in the gel coat, and the pits cause incident light to scatter, giving a whitish appearance. Penetrol fills in the pits and stops the light scattering.) One application of Penetrol will last almost an entire season.
The inside of the Bell canoe is woven Kevlar, which indeed scuffs and even fuzzes with normal use. Or it might also be some whitish blushing of the peculiar resin, due to a reaction with moisture, that Bell used during certain years, as is true on my black-gold Wildfire. After washing, I clean the entire interior with acetone, which eliminates the resin blush, and then apply Penetrol, which shines it up.
While Ed's is a long time standard for canoe parts, I would highly recommend the Conk contour seat made by Paul Conklin, a member of this forum. It's the most comfortable kneeling seat I've ever used in my 60+ years of canoeing. The front edge is not only curved downward but has a large radiused edge, so it doesn't cut into the back of your thigh. The back rail is straight, which supplies good support for seated paddling. It's laminated of two woods, so is both stronger and lighter than a solid ash or cherry seat. I installed one in my Bell Wildfire and it fit perfectly on the Bell drops. I also installed one on my SRT. I'm not sure whether Conk still sells them only through Hemlock Canoe, as they are now being used as standards by Colden Canoe and Savage River, but you can definitely buy the seats from Hemlock.
HERE is the product page from Hemlock and here is a Hemlock photo:
Here is my 15 year old Bell Wildfire with Conk seat installed and after being cleaned with acetone and Penetrol. It was in cruddy shape before the cleaning.
Here is a closeup of the interior (intended actually to show a gunwale repair):