How can connect many printer(up to 20) to one computer?
How can connect many manitor(up to 20)io one computer and send independent data to each of them?

The printers: You'll need 20 printers that have wireless connections. I don't think there is any adapters that will allow you to plug 20 printers into one port. Alternatively, you can just connect the printers up to various PC's and then share the printer access over a network. Although the PC will not be connected to the printers directly, it will still be able to use them as if it was.

As for the monitors - that's not going to happen. Connecting that many monitors to a PC and sending them all different data is just impossible. That said - why on earth would you want to do that anyway?!