Implementing remote desktops?

Question

linux

What is the best way to organize such work:
server
<- VIRTUAL MACHINE 1
<-- CLIENT
<--- CLIENT PROGRAM (VNC or something else)
<- VIRTUAL MACHINE 2 ...
Question:
1) what to raise on the server is economical in terms of resources than it will be possible to emulate different operating systems with the possibility of sharing resources. Those. there is 1GB RAM by default for user 1 - 500MB and for user 2 - 500MB. If at some point user 1 wants to use 750 MB of RAM and user 2 does not use his system, then user 1 can use the entire resource of user 2.
2) A convenient client for Win, Android, Linux to connect to the CLIENT with the ability to transfer audio and video with great frame clarity.
those. I, as a client, run the program (PROGRAM-CLIENT) and get to my virtual machine on the server. You can use VB or WM, but they eat too many resources and I don't know if they share resources, you can use VNC for the client and it's good, but there is no way to adjust the purity of frame updates on the screen.

Answer 1

Use XEN hypervisor or KVM. Install guset-tools in guest operating systems. Set up a balloon (just the thing that manages memory).
Use virt-manager as the management environment.
As web access - kimchi
Web client - any browser with HTML5 support