i don't think he would really notice the difference between a X2 and a opteron, its not like he is going to be running a high traffic site off it or 2 high load game servers at one time. a X2 would be really good in it. he can get away with running standard parts.
yes it generaly does, if it is not on there cpu support list and there is no bios update to support it. then the CPU core isnt supported. there is a 98% chance it will not work, unless there is a update.
natatkinson welcome to the forum
i doubt they are packet shaping but to test use utorrent and turn on encryption, if it goes faster on a few different torrents then they are, if it is the same speed then they are not.