Blue devil ???

I am also currently building this kit, with a LOT of additional scratchbuilt detail. It's been sitting unfinished on a shelf in my modelling workshop for the last 4 months, but a few days ago I decided to try and concentrate on finishing it. Currently I'm working on the 5" director radar, the funnel searchlight platforms and ladders, and the bridge/forward superstructure details. Hopefully I'll post some more photos soon (I posted some "work in progress" shots a few months ago - search for "Fletcher" and you'll probably find the thread)
I'm intending to scratchbuild the AA guns and other small fittings, and cast copies myself in white metal, as HR Products aren't available in the UK and ordering them from the US is a pain (they don't accept credit card payment). I definitely recommend using HR Products parts if you can get them however.

One small tip for this kit. If you assemble the 5" turrets according to the instructions, the gun barrels are noticeably too short. A fix for this is to cut the "breech" off the barrels, glue a short length of styrene rod of the same diameter onto the breech end of the barrel, and then fit the barrel into the turret blast bag from the outside, using the styrene rod as a "locating pin". This adds about 1cm to the length of the barrel.

It is certainly a huge amount of work to get this kit to a decent level of detail and accuracy, but (if you can put up with the inaccurate hull profile) it's (probably) easier and quicker than scratchbuilding.
Good luck, anyway! I'd be interested to see your work once you've started the build.

Read Jeff Herne's article describing his efforts to build the Lindberg Fletcher.    It is appropriately titled 'Trial by Ordeal'

http://www.steelnavy.com/BDFletcher.htm

Since Jeff wrote that article,  Toms Modelworks has released a photoetch set for the kit.  It helps but much of the kit is still overscale and/or grossly misshaped.

There used to be some replacement 5-inch gunhouses, but the company which manufactured them went out of business.   You will want to look into H&R Products for replacement 40mm guns.

Go to navsource.org and look at their selection of photos.    You will find that these ships did get somewhat worn looking, but did not get really rusty and ratty looking.  The crews who depended on them for their life took good care of them ( or at least the best care they could given the circumstances).