If you start over do you lose all your coins? I've finished everything in the game and was thinking about starting over but do not want to lose all the coins I purchased.

When you use Virtual Town's "Start Over" feature, you will keep all in-app purchases that you've made, but everything else in the game, including all coins the mayor has earned while playing the game, will be reset and you'll be back at the beginning of the game, ready to choose a new mayor.