Hi!
The decimal stuff is going to be overwritten, but there is going to be a new option to adjust the decimal places instead: http://i.imgur.com/0RdYWf0.png
All you need to do after update is to change that to 2, and you are set.
Making a brand new template is only possible by heavily modifying the plugin code – both javascript and the template files. As the method described in the results templating article, it’s the most you can do to have the plugin withstand upgrades.