Hi Chris,
It's really not that bad, so don't get too concerned. The resin parts sand just like plastic, although it's a softer material and will sand down much quicker than styrene.
White metal parts are easy, clean them up with a file or sanding stick, and prime them before you add them to the model. Both resin and white metal are best applied with CA, superglue.Same holds true for applying photoetched parts to resin.
With regards to building and painting, having done a few Fletchers in my day...
Attach the deck to the hull, and fill the seam. You'll want to fill the holes located where the depth charges go, as they will be replaced with PE parts including the depth charge storage racks on either side. You can keep the openings for the K-guns though.
The resin parts in the bridge replace the kit parts, and are drop ins. Tom also provides the brass midship bulwarks so you can replace the plastic parts if you so choose.
Once you have the hull and deck built and sanded, paint it. Use 5-N Navy Blue for the hull sides, and 20-B Deck Blue for the deck itself (they were different colors). You can also paint the lower hull Oxide Red (Anti-fouling, Sante Fe Boxcar red, Tuscan Red will do). Add your boot topping, a black stripe that demarcs the two colors on the hull.
Build your superstructure in sub-assemblies, again, vertical surfaces are 5-N, horizontal surfaces are 20-B. Always work from the centerline of the ship outwards, this prevents you from knocking off parts trying to reach in to paint, weather, or attach parts.
Your last step will be the outside rails on the main deck. I usually add these in after I've rigged the model. You can use fly-tying tippet to rig the model if you choose.
Hope this helps, drop me a line if you have any other questions.
Best,
Jeff Herne