You need to have the information available for each item to make a GCC for it.
Yes you need to register as a small batch manufacturer.
No you do not send a GCC with each sale. The GCC is sent if you sell wholesale or you put your items in a store. The store keeps the GCC on file.
You do not need to know anything to register, except the information that you need to answer the questions. If you do not have a website that has a dedicated contact link, and use your personal email link, you will receive an additional request to write a letter on letterhead. Do a search on small batch manufacturer on this forum, and you will find the instructions as to what to do.
If you are using all exempt materials and only those on list B. then you do not need to test, but you need to be sure that your products can withstand use and abuse testing and are age appropriate. So you need to be aware of what those requirements are and make your products accordingly.
Labeling. CPSIA labeling is a federal regulation. You are not exempt from labeling. If Michigan does not require state regisitration as a stuffed toy maker, then that is the only thing as per labeling that you are exempt from. Some states require registration as a stuffed toy manufacturer, mine is one of them. You receive a number that must be on a label attached to each toy. And there is their own state required testing .