What is the deal re: use of HU/HA characters/organisations etc. in orginal characters (who, of course, would be made available for use in HU/HA)?
For example, I'm thinking of creating an orginal character whose backstory includes being a scientist working on the Deuce project at Chegwin Technologies.
Is it just a matter of contacting the original creator to get permission?
How does that work for communal creations like Deuce, the HU Commander etc.?
Thanks.

I can't answer for everyone, but I do know that Wireless is pretty heavily set in the HUniverse timeline and there are even some cameos here and there. I usually ask people just to be safe

Yup, I think asking the creators is the right thing to do. For instance, fukujinzuke has made a lot of references to HU continuity and characters on SHELL, and I think he always asked the characters' creators first. The HU Commander and Deuce were created by Nepath, actually (even though other people have had a hand in designing her various appearances).