I can't supply any updated info, but DO make further inquiries and try to get there. I'd suggest contacting the Dunsmuir C of C for the latest. When I made the trek about 5 years ago, the community realized it had a potential attraction and was wrestling with ideas to improve access -- no ideas how far along they have come, though.
The walk up the tracks took about 30 minutes each way, and while not dangerous, was uncomfortable, because the base rock the tracks lie on is SHARP -- and there often is not enough room to find softer dirt.
I went in mid-summer and there's plenty of water; I believe that, similar to Burney Falls (only about another hour away -- try them, too!), Mossbrae is fed by year-round springs.