I like to overload methods to support more and more default cases. What is the performance impact of method overloading? From your experience, is it advisable to overload methods? What is the limit? What are the workarounds?
Overloading has no impact on performance; it's resolved by the compiler at compile-time.
As for design guidance, see the design guidelines:
http://msdn.microsoft.com/en-us/library/ms229029.aspx