Gatekeeper Though I agree this would be cool, most of it is not really viable as modding stands right now
1: There's simply no way to do this. As soon as you jump out of a planet, it's unloaded, inaccessible, and put into stasis, let alone you can't spawn actual ships
2: See 1
3: See 1
4: This is closer to being possible, but again because planets are put into stasis there'd be no way to actually detect how long it's been, and thus how many credits to reward. Also rewarding credits directly is impossible, though certain people have figured out ways to circumvent this using part replacement repair shenanigans
5: Probably the closest to being possible out of all of these. This is effectively possible by adding extra tiers of planets, identical to preexisting ones in every way except for an additional large target, and swarm chance respectively. The problem is these would be split near 50/50, though you could circumvent that by adding, lets say, 3 truly identical tiers and 1 "buffed" tier, leaving a total 20% chance for the "buffed" tier to spawn. It wouldn't be a perfect replica, and could cause various unwanted side-effects, but it'd (probably) get the job done
(Edit: managed to accidentally click send halfway into 5)