QUESTION: 
How is the telescope kept pointing the right way?

ANSWER from Andy Gerb on 29 March, 1996:
The telescope pointing is adjusted by means of heavy wheels inside the
satellite called "reaction wheels". When they turn they cause the
Hubble Telescope's pointing to change.

We keep a catalog of the exact locations of millions of stars called
"guide stars". When we point the Hubble Telescope, we find two guide
stars that are near the object we want to point at. A part of the
telescope called the "Fine Guidance Sensors" (everybody here just says
"FGS") senses the location of these guide stars and keeps the
telescope pointed so that they do not move.

Andy Gerb