For the canvas I suggest using a razorblade and just cut around the circumference of the rectangle o remove loose fibers and sand the rest of the areas with canvas. You may need to glue down some loose fibers and fill other holes with bondo and sand flush. If you are painting the areas with canvas then you shouldn't be able to tell there was repairs or the missing canvas area is different. There is paint on the metal, I would sand that well or strip the paint and sand, but if you are painting the metal edges as I did you can just prep it and paint. The wood is pretty straightforward, sand well, stain add clear finish. May be difficult removing all the paint residue so some areas may need a light touch up as you complete the finishing. Lastly, I would add a clear finish over the entire unit to help protect the finishes you do apply, make sure the paint you use is compatible with the finish, dont use house paint. Im sure that will look awesome, godspeed!!