Just got a new mac mini, Bluetooth keyboard and a logitech Bluetooth mouse I'm told that wifi and Bluetooth often interfere because there on the same 2.4 ghz signal this is bad for me because I can only acsess the Internet via wifi. Is it that bad or random, also is there a work around if anyone had this problem

One more thing I read that the mac mini speaker sucks should I buy external ones?

You shouldn't get any interference - Bluetooth uses frequency hopping and wi-fi uses DSS, they each appear as background noise to the other and shouldn’t cause any problems.

As for the speakers, I would definitely advise you to get the external ones.