I've read Kent's books as well. I liked them, but I found Bolitho to be two-dimensional. He never lived for me like Hornblower did. I love the way CS Forester built quirkiness into Hornblower's character, something Kent didn't do (or at least not as well). You're right about the homoeroticism. I could never quite figure out if their behavior was hinting at an "unnatural liaison" or if Kent was just trying to illustrate the more flowery language of friendships of that era. Forester, IMHO, was much clearer about that. I thought he did a really nice job or portraying a touching, non-romantic relationship in "Flying Colours", showing how Bush responded to his attention when they were traveling in France.
Parkinson also wrote a "biography" of Hornblower, designed to augment the novels and fill in the blanks. Of course it's not Forester, it's just another author playing with his characters, but it's interesting if you're a Hornblower aficionado.
Your recommendation of The Anatomy of Nelson's Ships is excellent. Peter Goodwin wrote a comprehensive book on the subject, one that carries a lot of credibility since he was responsible for HMS Victory for quite some time. His book is more of a reference than a good read, as it tends to be pretty dry. One that I've used a lot for reference on HMS Belvidera is a book on frigates by Robert Gardiner. Again, a great reference book, but also a much more interesting read.