Yes, there's nothing wrong with using a more powerful PSU (other than the fact that it may use more of your electricity). I've never heard of Echo Star as a PSU brand. Quality brands are Antec, Corsair, Thermaltake, OCZ, and PC Power & Cooling.
All processors have a heat-sink of some kind on them. It could be a chunk of metal with some fins (real high end ones can have what's called "heat pipes" as well) or a special designed block to allow the transfer of fluid for liquid cooling. A fan isn't truly necessary if the heat-sink is made well enough.
95% of the BTX systems i have seen (all dells) did not have a fan on the heat sink