I would like to host my website on a VPS, but I am kind of worried about my ability to keep the server running 24/7/365 and I can't afford downtime at the moment. Currently I have a shared linux reseller hosting account. How can I set up a VPS so that when it goes down, my shared hosting account will take over?
You'd need at least one additional load balancer. Have a look at this tutorial: http://www.howtoforge.com/high_availability_loadbalanced_apache_cluster