ISP connector
Space on PCBs is sparse… so, what to do with the ISP connector? See the discussion on microcontroller.net as well as the end of the Simple AVR programmers page.
C++ on Avr?
Sure, why not! But take care. E. g. about how to use C++ member funtions as interrupt handlers. Here, also see the information about Member Function Pointers and Pointers to Member functions.
Also quite interesting is the intelligent access to flash strings