Regarding the PAX, see the first post above with links and details. Please send me the changes you have made to the science so I can include that changes maybe in future? Anyone else is welcome to help out and send me their ideas and changes. (At nights I lay awake thinking how to fit an assembler in there to make exo suits.) So in due time I will still fiddle around with it.
I do plan to change my mall around when Factorio gets released to make that much awaited Spidertron and any other things I can add. The current version of the mall on my PC have a roboport moved and an assembler in there to make the refined hazard concrete.
I have something like that in the back of my mind. No, unfortunately I couldn't fit an assembler in there to make the standalone artileries.However, iirc, the wagon arty assembler can just be manually changed to produce the standalone ones.