Store Credit

Yes, additionally you can restrict an option to pay with store credit by another store credit product. All these things can be done in System > Configuration > Store Credit > General. This feature is configured on a store-view level:

Yes, this info is available in Magento admin panel under Reports > Credit Transactions History:

Additionally, on the Customer grid you will find the Store Credit column with the current customer redit balance info.

Get more reports with the specifically designed extension. Try the Advanced Reports module.

You need to create a store credit product in Catalog > Manage Products, the process is similar to a simple product creation. Once you complete all the steps, a product named “Store Credit” will be available in your store, and clients will be able to purchase it.