Share screens and PC to PC

 Share screens and PC to PC

For starters this program is awesome on how easy it is to use but i'm having trouble with two things, and i really hope its possible to do.

1. When my Android connects to my desktop PC it logs me out of my pc monitor. The object was to get both screen mirroring each other not one or the other. How do i do this?

2. The other use i want to get out of this program is to be able to jump on my laptop and share screens with my desktop pc (its an HTPC and ultimately it will only be connected to a TV with no keyboard or mouse). It says android or Mac... is this not intended for PC to PC? how do i do this?

PLEASE HELP  i'm new to the techie world. Also, what is the difference between VNC and RDP?