Would anybody have any suggestions as to some pieces I should play to get my technique and musical ability to the level of this (pleasant) nightmare?
I would suggest the following:
Ravel, La Valse

In all seriousness I do not think this is an unreasonable course of action if you have successfully played Hammerklavier. But if you really insist on playing other things, you may enjoy these:
Liszt Transcendental Etude no. 10
Rachmaninoff Etude-Tableaux Op. 39 No. 3
Lyapunov Transcendental Etude no. 6 linked to above, a particular favorite etude of mine, though I have not actually learned it yet myself
