By default it does use tcc on most platforms, because tcc is awesome for quickly compiling C, and so iteration while prototyping with it is usually much more enjoyable than with gcc, clang or msvc.

You can pass `-cc gcc` to use another C compiler for example, instead of tcc.

There is also a native backend, that generates executables directly, without generating C, then using a C compiler to compile it. You can use `-b native` to try it, instead of the more developed C backend. Note that the native backend, is still work in progress though and it does not support some language constructs.

This is the default but can be changed. I use clang on FreeBSD as a few tests break under tcc.

Yes.