This means that the "wallet.dat" file stores all of my bitcoin addresses?
If I have more bitcoin addresses in my wallet is this file (wallet.dat) bigger?
Is there a theoretical limit of the number of the bitcoin addresses in a wallet?
Is there a theoretical maximum of the number of the bitcoin addresses in the whole bitcoin system?
Is the bitcoin transfer slower to/from a bigger wallet than to/from a smaller?
As long as you keep your wallet, you can continue to receive coins to any address that wallet used previously.