Tested it on the beta, AI never circles their defenses around the planets, even though theoretically, geostationary orbits do exist meaning, some planet defenses could be closer and circle with the planet.

Gravity wells too small to support placement of a starbase via planet build menu, while via starbase item, they will be buildable.

Starbases bigger than planets

Bigger planets will be harder to defend btw.

Planetary atmosphere is not affected by nukes, if devs ever watched nuke detonations in atmosphere, clouds disappear near the mushrooms.

On some planets planet bombardment looks like from say CnC:Generals, where you have a line where a graphical effect ends and goes inside the terrain, but the gfx effect is visibly cut, where you can see a part of the effect and the other not, because it is inside the planet.

Retreating from the capital in a capital victory and going on the assault instead is how AI helps you with much easier wins, happens very often. So, first defend vs the blob, defeat the blob with a few capshps, counterattack, they will keep attacking instead of pulling everything to defend, the closer you get to their capital.