Question one, not sure. With us being quiet close to the end if there is a new one I doubt they will be a main character.
On a new Starmaker. There has been hints if there is a new Starmaker game it will have a complete different setting. Based in the same universe but a complete new roster of characters.
I have mixed feelings about this. If the characters are as engaging as the original cast, sure let's see where it goes. But I do feel like everything in Starmaker pretty much anchors around Anna and she is the secret sauce that keeps it all together.
At the very least my hope is if Kal does not wish to continue with Starmaker, he is open to someone else picking up the IP and we get a Starmaker Retold or something... Time will tell.