More spoilers up to the Eclipse (don't know if we should spoiler those, actually).
I absolutely agree, that's why I said quasi-sociopath. Maybe I just chose my words poorly. I was just saying that the Genon episode (and, before that, the death of the kid with the knight puppet), as shown in the river scene, was when he broke. He's not as strong as he thinks he is.
I largely agree. I wouldn't say his speech to Charlotte was complete BS, but he definitely wanted to impress her with it, and he didn't realize how much he actually believed what he said. I think he was just completely taken aback and forlorn at the fact that, yes, he does actually believe what he says about friendship, and "holy shit wait, so it actually hurts when a true friend leaves you?" He had this rigid, idealized vision of friendship that nobody up until then had managed to live up to, so when Guts turned out to be such a friend against all odds, he just didn't know how to handle it emotionally (as you said). Everything went according to keikaku, except Guts.
But other than Guts, he's never really cared about anyone other than as tools, right. Even Casca. She is his most valuable tool (until Guts), and certainly the most important member of the Hawks, but if she didn't show such martial prowess she'd just be another Corkus to him lol.
Alice : again, quasi-sociopath. Guts is the one exception. He genuinely cares for him as more than a tool.