This is the exact method to manage PPC, nothing more and nothing less. You have described all in short, others may have used lot of words to explain this Thanks!
The content network does not affect CTR for Adwords search-result ranking purposes. The reason you would separate content network from search network is to be able to better monitor the content network, where there is always some risk of fraud and poor-quality clicks, and where it's really a whole other ball game in terms of optimization.
im currently using approx 50 keywords for my single adgroup, im relativly new to adwords, any tips apart from the above? cheers