Who heads the International Space Station? Did Skylab return to earth?

Question

From what I know, astronauts from all over the world may stay at the ISS if they have PERMISSION... but who do they get permission from?

For the second question, did the first Skylab return to earth? What happened to it?

Answer 1

Intergovernmental agreement, establishing the International Space Station cooperative framework, has been signed by fourteen governments: the USA, Canada, Japan, the Russian Federation,ESA

The Intergovernmental Agreement allows the Space Station Partners States to extend their national jurisdiction in outer space, so the elements they provide (e.g. laboratories) are owned by the Partners States.

The basic rule is that 'each partner shall retain jurisdiction and control over the elements it registers and over personnel in or on the space station who are its nationals.
**but as gebobs mentioned NASA do manage the ISS

Answer 2

NASA is the designated manager of the ISS. See the link below describing the agreement.

Regarding SkyLab, what was left of it crashed into Australia in 1979.

Answer 3

Skylab burned up near Australia in 1979.

http://en.wikipedia.org/wiki/International_Space_Station

http://en.wikipedia.org/wiki/Skylab