What skills are necessary to become President(Rector, Chancellor)?
This will vary hugely between countries and individual universities.

In the UK most universities are formally led by a Chancellor: see this link for more information. Since their role is largely ceremonial, what is important is that they are people seen as being prestigious enough to represent the university. The current Chancellor of Oxford is Lord Patten, who used to be Governor of Hong Kong and chairman of the BBC trust. To the extent that a chancellor may sometimes publicly advocate for the university (especially for funding) it's also valuable for them to be something of an 'establishment' figure on good terms with those in positions of power.

If you mean to ask about the qualities of the person who actually controls the university (which in the UK would normally be the Vice-Chancellor) that deserves a separate answer, but one would expect them to be experts in the education sector and experienced at leading large complex organisations.

To answer your numbered questions:


It wouldn't normally be a requirement that they be a doctor.
I imagine speaking multiple languages would be a benefit (particularly speaking English in a non-English-speaking country), but I can't see it being a formal requirement.