Right now, a lot of developers understand how to use Github. For a variety of reasons, we have chosen to use Phabricator, and will remain on Phabricator for the time being.

I have to say that, mostly, https://reviews.bitcoinabc.org/source/bitcoin-abc/browse/master/CONTRIBUTING.md did a great job, and I was able to understand the basics.

we should also have a mechanism for people to chat with ABC team in real time.

Agree

The chat with ABC developers would be nice. The Contributing document was helpful with this platform and a few basics, although a few new developer doc pages could be useful.

For instance to help with onboarding new devs who might have otherwise worked on Bitcoin Core or other coins. There will probably be an assumed background in C++ and everything in Satoshi's paper, plus materials covered in some books and BIPs. Note: how about a ABCIP system? This might be helpful when working on big picture ideas like the ABC roadmap, and thrashing out good ways to implement works-in-progress and new ideas.

It would be good, I think, to have a high level overview of the components of ABC and how they interact. Everyone could contribute to a wiki-like page for example as they work along on reviews, testing, patching, bootcamp items and the release process.

A literate style of programming in docs and perhaps BIP/ABCIP items could help in terms of faster onboarding and a more agile method with CI. When code becomes obvious to even new contributors, ABC will have reached a new height in high quality documentation in my view. DASH goes part pay to this ideal, with top cross-referencing etc.