Regarding the pros & cons of different designs, here is a pretty good first-buyer's guide:
http://astronomy.concreteairship.com/scope.htm
A bit out of date, with a lot more good telescopes available now for less. But most of the information is still very much relevant.
Sky & Telescope's website also has some articles worth reading. Try starting from here:
http://skyandtelescope.com/howto/scopes/