Nice info!

One thing keeps me puzzled. The contents of wallet.dat do change (additional data added) upon new btc address/keys creation right?
If you have a wallet.dat file stored somewhere in a safe and not used for a few years, and you actually use another wallet.dat (a copy of the safely stored one), what happens once you decide to bring up the safely stored wallet.dat on a different PC after some time?
Do you have all your funds or only the funds that you gained with the old keys available on both wallet.dats?

Not sure If a explained my issue here clearly..