What features of C++ lead to extra resource usage that I should be aware of when developing for an embedded system?
Look at the MISRA (Motor Industry Software Reliability Association) guidelines for safe C. They were designed specifically for coding in C and C++ for embedded application.

Wikipedia:
https://en.wikipedia.org/wiki/MISRA_C

And the MISRA-C home page:
http://www.misra-c.com/