From everything I've read and researched over the years,it's pretty much a given that Hoover's supposed fetish for cross dressing is really an urban legend.As far as his sexual preference,the Clyde Tolson rumor is somewhat feasible,however some who knew Hoover have stated that he seemed more of an asexual person.
He appears to be a guy who lived for his work,and it would not surprise me if he died a virgin.Hoover was an extremely weird guy,and according to some sources,he actually used Astroturf on his lawn so it was always neat and perfect.
Hoover was more comfortable around his own gender,was obsessed with neatness and routine,and IMHO,pretty much borderline nuts.