[Koha] Question about instances and VPS

I install Koha on a VPS. I create instances for my student and other librarians to test and learn about Koha. I have some questions: 1. How many instances can i create? (it's subdomain www.xxx.mylibrary.com) 2. And for example, 100-200 instances, is that problem with my VPS when they all work together? Do i have to care about my VPS's RAM, chipset, HDD, internet bandwidth, or something like that? Thanks!