You can use a First Hop Redundancy Protocol of your choice, HSRP, VRRP or GLBP.. you'll have to research on these because there's so many bells and whistles but pretty easy for a basic set up. The standby takes over when active fails or link goes down or link speed goes below a certain threshold etc there's just tonnes of things you can tweak. You'd need a redundant connection to the outside ISP (I am assuming that's the set up you have in mind).
As for automatically sharing the same configuration, I could be wrong but I am not so sure routers can automatically share changes between each other without admin intervention, maybe u can use CSM to push configs to both routers.
