All of this and all of what rorrr mentioned should be a primary thought. I always hope people say, "duh, that's obvious" but I've worked too many places where ramp up on a project is a hodge podge of copy pasted scripts, years-old info on a wiki and "good luck, take a few weeks to get setup".

At the very least, all of my projects can be developed on in a live testing environment after one step after check out and it works everywhere the toolchain works. It lowers barrier of entry for developers and for users that want or need to build from source.