While there is a thread tracking the problems maintaining an LMDE based on Squeeze, this forum will not be the best place to ask questions regarding it. The official Debian forums would be a better place.
Do the errors prevent your Debian usage at all? They may not be worth worrying about.
And finally, Debian can be a tricky beast to work with. If you want a Linux operating system that is much easier to use, I would recommend Linux Mint 13 or straight Ubuntu. They will be much easier to understand for a novice.