Regarding Trip and his possible feelings for Archer... by and large, given that LGBTQ is probably pretty much accepted even in the primitive (by Trek standards) 22nd century, I don't see why Trip and Archer wouldn't have acted on their feelings, given that they weren't always in the same line of command. I think they were just really good friends.
On the other hand, I do like the explanation Siddig provided, re him and Garak... if Dax came back as a male, even if nothing happened between him and Bashir, it might at least make him reconsider certain presumptions.