See the passport requirements for travel under the Visa Waiver Program. (The VWP applies to German citizens among others.) It says this about biometric passports:
October 26, 2006 – Each Visa Waiver Program passport issued on or
after this date must be an electronic passport with a digital chip
containing biometric information about the passport owner.
My passport doesn’t contain fingerprints (to my knowledge), but that wasn’t a problem (2011). What happens is they take your fingerprints & photograph when entering the country. (If the passport does contain your fingerprint data already, I’m not sure if they’d just read that or take the fingerprints again.)
So yes, your friend should be fine.
To be more precise, the passport only needs to be electronic & biometric if it was issued on or after October 26, 2006. (Except for citizens of Czech Republic, Estonia, Slovakia, Hungary, Latvia, Lithuania, Republic of Malta, South Korea, and Greece who always need an electronic passport.) In any case it needs to be machine readable (i.e. contain two lines of text with numbers and chevrons (<<<) at the bottom).
To answer your updated question:
And how long has the passport to be valid? Is it okay if it expires on
the day after his return date?
For citizens of Germany (and most other ESTA-eligible countries), yes, this is okay; no extra validity is required. The passport only needs to be valid for the duration of the visit.
A document entitled Six-month Club Updates from a U.S. Customs and Border Protection web page (found through this question) has this to say:
Visitors traveling to the United States are required to be in
possession of passports that are valid for six months beyond the
period of their intended stay in the United States. Citizens of the
countries listed below are exempt the six-month rule and need only
have a passport valid for their intended period of stay.
Germany is on the (long) list of counties that follows.
Finally, tell your friend to just go ahead with the ESTA application already (unless the trip is a very long time away; the authorisation is valid for multiple trips over a period of two years). As someone wrote on the internets:
Have you signed up for the ESTA program yet…if not you need to do
it right away. Getting your Esta clearance is another confirmation of
your passport being fine.
Credit:stackoverflow.com‘