1- Great
2- WHMCS Did you try this steps ?
3- convert to cloudlinux is very easy if you follow steps of usmannasir Here >> https://community.cyberpanel.net/t/1-convert-cyberpanel-to-cloudlinux-os-and-install-cagefs/174
5- Virtualizor or any other option is different as cyberpanel is CP but it have option such as VMM https://cyberpanel.net/docs/rc-installing-cyberpanel-vmm-virtual-machine-manager/
6- for high availability, I recommend use cyberpanel cloud as it’s more easy for you, there is another options but you need experience … please not I’m just member same as you and just help others using my experience 
7- yes sure cloud will help you much