You write in the FAQ that you don't intend to enable the import of GC3 ship designs. I'd like to ask you to reconsider this. All the millions of man-hours put by talented people into GC3 designs over the last years. And you do not want to utilize this treasure for your new game? Wouldn't this be an additional selling point?
One reason you give is that the GC4 parts look better. But I don't see why this should be a problem. You wouldn't have to do any redesign on the old parts. Just include them in GC4 as they are and code an import algorithm into the (supposed) new format. As a SW developer myself, to me this sounds like a few days of work for one guy. This way people could rework their old designs step-by-step with the new, better looking parts, if they want.
Also, I think a GC3->GC4 "cross-download" infrastructure for ships on Steam workshop would be cool but is not absolutely required. I'd be happy with a way to just import the old ship files from my harddrive.
BTW, I still think that providing no way to import GC2 ships to GC3 was a big mistake.