1. One of my extensions doesn't work with this theme

This theme is not compatible with all third-party extensions. During using the template, there will appear conflicts when there are some extensions not working with this theme. It is because the extension and the theme override the same Magento template file, resulting in the problem.

To resolve this case, you need to customize the theme and merge two conflicting template files into one template file. It is also recommended that this is not a specific issue, very common rule of all Magento themes and extensions.

2. One of the features stopped working after the third-party extension was installed

There can be a conflict if the extension and the theme override the same Magento template file. You should contact the author of the extension for more information. Also, check your log files in var/log/ (log settings should be enabled in System >Config> Developer) for more details.