About Stella-Mac-Claire. I personally think that Stella and Claire haven't been like bff, but still quite close. I think Stel was casual with Mac being married to her, but there might be one or another situation where Mac had to suffer from Claire's jealousy. Not like she generally would have suspected him to have an affair with Stella, rather him spending so much time in the office and so subsequently with her, so she felt she sometimes came second.
I think as well that Mac was always fond of Stel and maybe even had a little let say crush on her, but never showed it, not even to Stella. Stella on the other hand will have played out more obvious her affection for him like she does these days... touching him and being sometimes a bit bolder than the rest of the team, e.g. waiting in his office chair without asking him if this is okay.
Also, I think she never actually got his little affection for her til now. I don't think she really believes him being attracted to her (I mean in another way than any man must be attracted to her except when they're blind or dead!). Maybe that's the reason she is so reluctant these days to push things more forwards...
As for today, I think Mac doesn't compare Stella and Claire. I think that he can't judge who comes first and second. I rather see him realizing now that his deepest grief lays behind him, what an amazing woman Stella, not just as a friend. Like someone cool posted... Claire is his past, Stella is his future - not to compare at all. And Stella always accepting Claire as a big part of Mac might support this newest realization.
As for them having hit the sheets in the past... nah! WAY to much unresolved sexual tension still ongoing. Hello?! The eye sex they both have every week tells me they still wish to undress each other and haven't come to that point yet!
No, it just seems unlikely, cause they are both strong characters who pull themselves together even in tough situations. I didn't expect both to put a one nighter over their deep friendship. *sigh*
