How to fix/clean a bike to look bran new?

So i garbaged picked a bike from my neighbors, it is the cutest bike i have ever seen. Unfortunately it is covered with rust everywhere and the tires are REALLY flat. I know i am going to have to replace the bike seat, and chain, but i was wondering how you get rust off of metal and how much paint costs for a bike? Along with how much it would cost to replace the tires if necessary. Thank you so much for taking the time to answer my questions i really appreciate it