I have a project that uses Base SDK 10.4. For some reason (using LLVM C++ standard library) I need to set Deployment Target to 10.7. But when I try to build project I have an error: 'Availability.h' file not found. So I have a main question: is it possible to use Base SDK older then Deployment Target?
No, you can have a deployment target lower than the base SDK, but you cannot deploy for 10.7 while compiling against 10.4.