Elves and humans, yes. There's some official writing that theorizes that Khajiits have interbred with wood elves. I don't think there's any current evidence that Argonians can interbreed with the other races. I don't kinow about orcs either.
Mara
Orcs, yes: the Gray Prince, his father a vampire, but not an orcrish one.
I'm almost certain Argonians can mate with, but not so clear on the breeding aspect. I would say yes, but I can't back it up with anything other than hearsay in-game.
Stats and certain skillpoints, though game mechanics, are representative of inheritable traits. Orcs are naturally stronger than the other races, Nords are naturally tougher. I also believe that even without training, Redguards have a natural talent with arms. And no race will ever jump higher than a Khajiit, or swim faster than an Argonian. Elves have a greater affinity for magic than non-mer.
And with the example I quoted, again, I say he got it backward. What he listed as traits are the racially-powered ones, while saying he wouldn't recieve minor physical traits. I said he wouldn't get those race-based traits, and would get the father's physical ones, like dusky skin and red-tinted eyes.
I would agree with Scow on the arrangement of the traits. I would disagree with his first statement, however: while races have predispositions towards certains paths and skills, a khajiit who goes warrior and does not train his stealth and acrobatics skills could be outdone by an orc who went acrobat. It's all about which muscles you train, in the end, and which skills you use. A khajiit acrobat would certainly outclass an orcrish one, yes, but not all khajiit would do so. To assume so would completely invalidate the point of the gameplay systems, for starters. Also, it just makes sense that way.