So you implemented a technology without knowing what it does? Was any attempt made to read the documentation? Does the current configuration work and you're just curious or is something broken and you're taking the long road around to figuring out how to fix it?

addif creates a new virtual interface (like ce0:2)
There are two 'UP's because you're 'UP'ing two interfaces, the real and virtual.
failover is an instruction that tells the kernel you need one interface to "fail over" to the next.