Question

How to calculate nummber of requests my database can handle?

Answer 1

That depends entirely on the structure of your website. If it’s just a few static web pages without server-side computation, and the server isn’t doing anything else, then you’ll be bandwidth limited. Your bandwidth for people on your WiFi LAN will likely be much higher than anything you can achieve from the rest of the Internet - although getting smart phones on your WiFi network to connect your website by name may be challenging (unless you run your own DNS server too.)