I'm
German so of course I'll comment on the names :-)
Lucas - very popular, I know about 6 guys with that name
Wanja - never heard it before and I doubt it's
German; it looks more Russian
Joschi - again, I never heard someone actually being called that but maybe as a nn for
JohannesJannis - not very common, but my brother has a class mate with that name
Kiri - is the name of a cheese brand here, so I'm sure it's not used very often
Fränk - never seen that, but
Frank is quite popular
Prisca - a female name (as you guessed correctly); very old-fashioned and I've only seen it on a Catholic nun