Record a list of installed packages and configurations before installing a higher version of Ubuntu?

Question

I now have 12.04 installed, and would like to install 14.04.

1. Is it recommended to create a list of installed packages, so that I can install them back after installing 14.04?

   What about those packages installed with no record in dpkg, such as those installed by configure, make and make install from source?

   If yes, how?

2. Is it also recommended to save the configurations of 12.04 and installed packages somewhere, so that I can make the same configurations after installing 14.04?

   If yes, how to do that (efficiently)?

Thanks.