1) In recent build there is a feature called minimal perspective and you can quickly switch to it by double clicking the tab of the file. It is not full screen but it is quite close to it.
2) Because most of the times it is better to see all function names available
3) It works without problems, here. If it doesn't ask a MinGW support site, here we support C::B only, not all the compilers it users to build code.