http://www.uesp.net/wiki/Oblivion:Esbern
Do you think this means he will probably be a nord?
Definitely. It's a Nordic name. THere's a famous Swedish jazz musician who died a couple of years ago, his name was Esbj?rn. Esbern might be the Icelandic version.
...but not a relative. None of them have a family name so there's no reason to suspect them being related, if they aren't the same person that is. Who knows? Maybe he was working undercover?
And about the age - he's a dragonborn. Maybe dragonborns can live longer?