Expecting logic from a guy like may be asking too much!

That's not being bi, that's situational heterosexuality. No evidence he feels any actual attraction to women.

Manic or coked up? Given the setting and everything that happens later, the later seems more likely. That isn't to say he isn't also bipolar, but I don't think his behavior in that scene can be counted as evidence for it.

She wasn't really in her right mind at the time though, between being knocked flat by the break-up and being drunk/high herself.

I can see where you're coming from on Justin's likability even if I disagree, but the idea of anyone relating to Mickey kind of scares me. Brian was no role model, but at least he wasn't a violent quasi-sociopath!

I'm gonna go ahead and interpret that as a doctor who reference.