Best of luck! I did a 'QuadMod' awhile back but I didn't really mess with much on how the planets themselves acted. I just 'beefed up' the systems. The 'organic plant thingy system' was actually alive and pulled things in like a black hole, I had a storm system that had planets, comets hid ships (like stealth armor) and such stuff. You are quite welcome to look at it/incorporate what you want if anything suits your fancy.
Now as to things I would like to see (things I never got around to or totally understood). Colonizable Asteroids! (I know it has something to do with just using the asteroid picture and the small planet stats for everything else). Machine planets! (I don't know, maybe use a borg cube for the graphic
).
I don't know if all the abilities work yet in the abilities.txt but alot of them would be neat additions for planets (ie built in abilities like 'Research Point Generation'-"An all knowing Hermit lives here and imparts his wisdom upon you") I did a map before with stats like that, as well as planets with ground combat bonuses, resource generation etc but most of them did not work.
Ah well, again best of luck. Modding is a fun experience!