Q: What do Eggs & Bunnies have to do with Easter?

A: Absolutely nothing.

Spring has been celebrated throughout time.  The weather gets warmer, food more plentiful, & of course spring is the season of new life & fertility.  That is where bunnies and eggs come in.  As a representation & celebration of fertility, celebrated by pagans during their spring celebration Ostara.  

Romans traveled Europe assimilating people to Christianity and since that was not an easy task the Romans took customs from different religions to make Christianity more familiar to Pagans, thus making the assimilation process easier.  Rather than making Pagans feel like a new religion was being forced upon them.

So basically the Christians tricked the Pagans into religious conversion.