They hired me despite my not knowing any Java. I was there for close to 5 years and did my share of interviewing and I haven't seen a single instance where lack of specific programming language skill was brought up as a reason to reject the candidate. But yeh, the whole hiring process is more random than it should be.
Depends. Is the person a polyglot with extensive experience in more than one language of a similar paradigm? If so ... it's just learning the syntax, libraries and idioms ... it's not rocket science.