High performance and complex endorsements are not category and class specific. If you wanted to get both at the same time, you would have to find an airplane that is BOTH high performance and complex, such as a C182RG, C210, C310, PA32R-301, BE36A, etc...

Better yet, find a DC3 and get your hp, complex and tailwheel all at the same time!

There is no specific time requirement for the endorsements. You just have to log ground and flight instruction and receive the endorsements from your CFI.