I totally agree with 2 through 4, although rebuilding heavy lift rockets like the Saturn V is not really necessary.
If we commit to building a space station that will serve as a launch platform, then Saturn Vs are not necessary since you don't need them to take you all the way to the moon. All you need is a rocket powerfully enough to take you to the station.
To make the rest of the trip, technology already under development, rail gun type perhaps, could be used to propel you to the moon. By the time we get around to building all of this fancy infrastructure, rail guns and stuff like that may very well be common place.

Decisions we would have to make before in my opinion that we would have to make before we would have a moon-based radiotelescope

1. Rebuild our heavy lift rockets.
2. Continue to fund a "space station" and actually make it a platform to as a go between orbit and the moon or beyond
3. Implement infrastructure that would require 1 and 2 where you would have "shuttle" craft to go between orbit and the moon.
4. An orbital platform around the moon with the same function as the "space station"

Then you might be able to put down a permanent lunar base and implement the infrastructure needed to construct the radiotelescope.

It might seem silly but look at the infrastructure it took to build the Transcontinental railroad.