Fab is a build system that helps you build optimally every time.
Dependencies within the project are discovered automatically by examining the source files.
The caching daemon runs in the background so that expensive tasks, like building the dependency graph, are only perfomed once. Incremental builds are really fast.
The caching daemon receives filesystem events so it already knows what's changed when you start a build. It can even start the build automatically.
Every project belongs to a larger project. Use the same build description files whether you're building just this library, or the whole product.
Absolutely. However, not all features are complete yet, and until the project reaches v1.0, everything is subject to change.