Pre: I\'ve been working in VIM for like a year already. Lots of great things: combinations, scripts. Whenever I\'m editing something in a different editor,
You could try eclim, which is a way to use some Eclipse features in Vim.
For C/C++, it provides :
:CSearchContext):CCallHierarchy):Validate)It is not great, but it can help in some cases.
Regarding automatic code completion, I primarily use OmniCppComplete, which is using tags to provide Context aware code completion. It is not that bad.
As advised by Luc Hermitte, you can also use clang_complete which does not need ctags, but needs clang installed.