Need help with an auction site that is a wordpress setup

We are building a website that will be used to sell lots of water to farmers, it will be an auction site where we will put up an auction about what water we have for sale with all the information to go with it. We are currently using an Ultimate Auction plugin which seems good. We are wanting help to make a signup and login feature, where a client will sign up with their name, username, address, phone number, email and they will have to sign up and login to be able to bid on water, this is the part we don't know how to do. We don't want them to be able to login to the back end of word press, and we need it so when they place a bid through the plugin, it shows their username and bid amount, and if they win the auction, an email will be sent to them confirming it, the sign up and login may be able to be completed with a plugin, or the Ultimate Auction plugin might have a feature to be able to do it.