regarding the constructor problem: imo it would be helpful if they changes the default scaling of the auto-designed constructors. that script is pretty weak now - it will just fill up all hull space with the best (most expensive) life supports, so in the late game an auto-designed constructor can be quite expensive due to haveing 10 life supports that each cost 50 manufacturing or something.
they should probably change the scaling to put in more construction modules if the hull size allows it. IMO it's ok that the auto-design comes with a sensor, an engine and one life support, but the remaining hull points should be filled with construction modules. you can easily put 2-3 modules on a cargo hull with some hull size increase tech (and/or the reduced size of support modules you can pick early on).
i guess they could also branch out at some point and have to auto-designs - one with extra life supports that you can use for building new stations in deep space and one "upgrade constructor" that only has the bare minimum of required stuff (1-2 engines, maybe a sensor, all else construction modules) that is used by the "request constructor" command.
that alone would probably go a long way without actually changing anything about the command itself, just some tags in the XML.