http://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_p...
http://en.wikipedia.org/wiki/Lunar_Atmosphere_and_Dust_Envir...
About the far side of the moon, there is little reason to put a telescope there. It is much easier to put one in orbit around the earch, sun or an earth-sun Lagrange point.
As for manned space exploration versus robotic, I think that is a debate for an other day.
I also imagine there are cost savings by having it sit on the surface of a moon than being its own satellite. No need for worry about orbit corrections or strict weight limitations. The Tsiolkovskiy crater is pretty flat and would make a good candidate for a telescope which would have long antenna arrays laying on the surface.
L2 point would give you almost all the benefits with a lot less risk and cost.
I'd love to see the next POTUS make this a priority. Yeah, Orion and the SLS are impressive, but they're mostly fighting yesterday's battles - pretty much a souped up Apollo for similar big feel-good missions where men and women go into LEO/moon/asteroids/maybe-mars for a very short time and fly right back. Why can't we also fund a farside telescope that could work for decades 24/7 providing space science advantages we simply cannot get any other way?