What you can/can not do with the assets?
You CAN use assets/modified assets in any type of projects, commercials right included, for unlimited number of projects, as long as you are a part of the team that is working on the project.
You CAN NOT sell the assets to other individuals/studios. For example: you can't publish and sell assets on Game Asset Store like Unity Asset Store.
What is my workflow?
You give me your character ideas + references.
I will sketch based on your idea and we will work on it until you are happy.
I will make the line art. Then add color after that (for Standard package+). We will work on it until you are happy with the colors.
I will create separate parts of your characters (only available with Premium package). Ready for you to create animations in your project.