>1. Is the only way to create a composite class stored in a VCX file through the CREATE CLASS command?

That's the only way to do it programmatically, as far as I know. I guess you could try building the vcx yourself, but I wouldn't want to.

>2. Using the CREATE CLASS command, I will need to close the window programmatically. I have tried an ACTIVATE WINDOW "Class Designer" and a KEYBOARD "{Ctrl-W}" with no success. How can I close the designer window?

This works for me-

ACTIVATE WINDOW "Class designer"
KEYBOARD '{CTRL+W}'