"1. How the heck do I retrofit obsolete units such as satellites, troops, etc.?"
You can't upgrade units, only scrap/jettison them.
"2. The lists seem to show all possible areas but not what they don't have. Does this require intelligence projects?"
More or less. It would be very cheesy if you got buckets of free intel just by going into the trade screen. It's easier in a PBW game where you can actually talk to the other side.
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"What's more, as long as those projects are incomplete they are vulnerable to intel attacks. Best to get them out of the labs and into production asap."
What about after turn one, where you have 50k in one project? The divide evenly method would only have 12.5k lost in one project.