I'm going to deal with these one at a time, to avoid really long messages.
* The Earth texture was created by NASA using data from the MODIS
instrument aboard the Terra satellite.? Further information is
available
from http://earthobservatory.nasa.gov/Newsroom/BlueMarble/
If it was really created by NASA -- which is part of the US government -- then
it is in the public domain, like all creations of the US government.
If it was created (1) by a third party (like JPL) under contract with the
government, or (2) was modified (to a degree significant for copyright) by a
third party who is not part of the government, then it is under copyright and
a license is needed from whoever has the copyright.
You can probably find out which it is. :-)
Anyway, from http://earthobservatory.nasa.gov/masthead.html,
"Any and all materials published on the Earth Observatory are freely available
for re-publication or re-use, except where copyright is indicated."
I suspect that "re-use" is intended to include modification (which is
necessary for many scientific puposes) here. Perhaps if the site managers
for Earth Observatory they were asked to clarify that, they would.
