Here you have the complete change log from the first version to the v1.2. Note that M means modified, A added and D deleted.
About styling your theme we always recommend to use the custom.css feature included with the theme. You can use the custom css field you will find in the option panel. All the styles included there wont be removed or overwriten with updated files.
Anyway, remember to back up your files always you update your theme and if you have any question contact us always you need it.