The autoexec.cfg isn't necessary and you can ignore the error. If you really want to get rid of it, just create an empty file with that name and put it in the base directory. Now, as far as the assets2.pk3 file, you need to copy that from a 1.03 patched client. It will be in the gamedata/base directory.
"Do you expect me to talk?"
"No, Mr. Bond, I expect you to DIE."