cloud solution. virtualise windows 7 over WAN for multiple clients and own cloud

Hi i basically i need some research done and a plan made on how to create my own cloud for my own clients and remote desktop virtualisation. One that will work with both MAC and Windows. Open source solutions i like or hyper v I run an IT Business and i wish to have my clients backing up important files to an offsite cloud which then i can host and they can login through a web interface and retrieve data on there mobile or remote computer. So this one would work over the internet. And another design which would stay in house of the business but accessed remotely on mobile devices and computers. Also i want to know how i can publish multiple virtual desktops to different users over the internet from different WANS or business's. Im thinking Hyper V is there a way to do it that they can remotely login to there own virtualized machine without hitting the actual server that hosts the hyper. I want them to directly login to there virtualised machine without logging off the physical machine user or system administrator. I dont have a static wan ip so i use no ip. How would the users login?