tathisit parent
Not an apple user, but I've heard that xcode is an ide+build system. Which means that you can't compile an application if you don't have the exact version of xcode installed. How true is that?
I'm not sure what you mean by "the exact version of xcode installed" but you can compile most applications with any recent version. Of course when new SDKs are released you need to update the Xcode version but it's not a big deal (and maybe a once a year thing).
It is an IDE + build system but you can totally write code in a different editor and compile it on the command line with xcodebuild.
They're part of Xcode package but they can also be installed separately IIRC.