1) This is expected. If you want to have a full test environment, just sign up for a free trial account at https://diy.seosamba.com/
and upload an ecommerce theme there. OR download the system and install it on your own server.
2.) Yes, you just purchase the plugin, and the platform is free. We offer hosting services from https://diy.seosamba.com/
if you need it.
3.) Yes, you still need SSL on your site to do this. You can also purchase a SSL certificate from https://diy.seosamba.com/
4.) You can't. See answers to question 1.