RChilli API performs much faster and much better with the higher configuration. An EC2 instance or Google VM instance or any service provider instance will work for installing RChilli API.
Absolutely SSD performs better read and writes so It will be slightly faster than HDD
RChilli API can be installed on both HDD and SSD. As, SSDs do read and write much faster than traditional hard disks, so there is a significant improvement in the speed, not much difference. But it is recommended to use SSD. Rest, HDD will also be fine.
If you still have a question regarding the server configurations, you can always contact RChilli Support via creating a ticket at RChilli HelpDesk or simply by sending an email at email@example.com.