1. It's possible the wallet.dat is encrypted twice (by Bitcoin Core and TrueCrypt).
It is a real possibility, especially if the wallet.dat was not created like pre-2011 when there was no password protection of any kind. Although there is also a small chance of the password of both encryption stores to be the same.
I also liked that this software allowed you to move the mouse around to create entropy, I wonder why Bitcoin wallet generation does not include this feature.
Nowadays it's mostly not recommended to use any kind of user-action-derived data for entropy generation, since humans are incredibly bad at creating true randomness, even when trying their best to do 'random' things such as mouse movements or even selecting a random sequence of zeroes and ones.
There is a number of scientific publications on this too, as mentioned in this StackExchange answer:
https://crypto.stackexchange.com/a/87982I remember that bitaddress.org and GnuPG also listen for user-generated keystrokes and turn that into entropy, somehow, but they combine it with other sources of entropy.