…and send a message there? That’s where all the devs hang out, and where you are more likely to get a response, and hopefully people interested in contributing.
You actually can generate a Haiku image with native development tools (and headers) already on it - this will prevent you from having to install the BeOS versions.
For native Haiku development, this would definitely be the best decision. Unfortunately there are no official images yet with these included - and you either must download a 3rd party release from haikuware.com or create your own image with the optional “Development” package.
I’ll definitely give a try to the Senryu Developer Edition Vmware Image and compare it with the setup I manually built. Hopefully they are not much different.