I tried it and the stars on the main card did effect the damage output (which is weird, because I got the same damage when I tried Chaprition 1 and 2 stars a few days ago), I’ll be editing the guide tomorrow. And no, the sub cards are supposed to be providing the stat for the main card. From what I remembered my 1&2 chap had the same sub card stat too…
The thing about sp is that the summon isn’t going to be the only thing you’re using. Without natural sp recovery you’ll realized how fast you can run out of sp. I grinded with a party earlier today and my sp often dried up even when I desummon it midway.