Hi,
1. Some are included, some are available for free on our marketplace or on our github.
All in all, there are around 200 payment plugins available for HikaShop. Some included, some developed by us and free but not included, some developed by us and not free and not included, some developed by others but free, some developed by others and not free.
2. There is no limit. However, this is for the installation and use. For services like the cron task service, user support, updates via the joomla update system, only 1 website per purchase is supported. If you want something completely unlimited, you have this one:
www.hikashop.com/extensions/hika-multisites.html
With it, you can enter the domain names of the websites you want to use it on and you'll get access to these services for all of them.
3. After one year, your subscription to the services I was talking above expires. This means that you can't use the cron task, ask us for support, or update HikaShop. You can still use your HikaShop for as long as you want. If you want to extend the access to these, it costs 60€ per year.