Yes, they are pretty impressive considering the form factor!
You
can get new frets from B&O - at least black and white are
available, I think also a darker shade of gray and perhaps other colours
too. The standard blacks are ~200€ pair so not exactly cheap... not
impossible to do yourself though with any colour you like, and there are
some reclothing services as well although I haven't personally tried
those. It would be a shame to destroy good black frets just to get
another colour, though.
The serial number is on the type sticker on the connector flap, peek on the underside while it's up