is your valuable information about Forrest's attack on the fort at Athens available there?

It isn't posted there. Most of it is just paraphrase of actual reports. I plan to rewrite it as an assembly of straight report quotations and footnote.

was the fort at Sulphur Springs towards Ardmore, or near Elkmont on Sulphur Creek? I'm not at all clear on the modern location

Does the reference to a fort at Elkmont refer to the blockhouse at Sulphur Creek? Is this the same thing? The Sulphur Creek blockhouse which guarded the railway trestle north of Athens was one of the largest works on the Decatur to Nashville rail line, and was located just east of the bridge along a ridge stretching out into the Sulphur Creek valley.

My dad visited the site a few years ago on a trip to see Franklin with Dr. Buck. They just stopped for a moment to see it. The location is apparently privately owned and difficult to find.