Memory is a little hazy on FO3.
Didn't Liberty Prime get destroyed at the end of FO3?? Is this the same Liberty Prime? Or a new one?
I vaguely remember Madison saying something about it, can't quite remember it now tho.

How did they manage to transport it all the way from Capital Wasteland to the Commonwealth?

It is the same one from fo3, there was only one, they salvaged what was left after they attacked the enclave base in brokensteel

Ah I see...thanks!
I like how they tied FO3 to this one.