Well, I've worked on this piece recently and I can give some suggestions! First of all, it is very true that this piece requires a lot of stringth! Why? I'll give the reason. First of all, the passage starting with the Eb major chord is extremely powerful and basically, the power goes on till the middle section (or just a few chords before). Then u have a build up again and an explosive final passage!
Finger push-ups are a must! Plus, remember that this is a piece in which you should not hold back! Take lots of risks; a cautious approach will mar and spoil the fire this piece has! Also, although u have to play the opening passages quite softly, but there has to be some crescendos and de-.... there also, else it sounds dull!
Another important point is that with too much stress on the outer movements, the middle section can get neglected. You should be able to play the entire left hand arpeggios without smudges and at the pace of, say, revolutionary etude (of course, this is only for practice, the actual pace is slower!)
But the most imporant thing is the character of this piece! I interpret it this way:
1st page: Napoleon Bonaparte marching with his army to Russia, the Russian peasants are mystified with the sound of the approaching enemy; hence, show the Napoleon's confident march, and the Russian commoners' terror!
2nd page: The battle begins, cannons are being fired, the soldiers are fighting... Lot of power! The napoleon is initially winning.
Middle section: The Russians have drawn the army in to Siberia, where they cut off the supplies of the french. Winter has set in and the scene is pathetic for the french. One by one, their men are passing away!
Recapitulation: The Russians are regrouping their army and building it up for the final assault!
The attack comes again in the ff section, this time it is the Russians!
The finale: The russians are driving out the french from thier country! ===>Very very powerful ( for me the highilight of this piece!).