No worry and thanks for your detail info.
1. Please try to increase your WP Memory Limit into 64MB or 128MB (recommended). Please check our documentation about it here http://support.jegtheme.com/documentation/system-status/ then jump into Memory Limit section.
2. For JNews – Customize Detail Category, you can using JNews – Extended Category Option plugin instead. For the option, you can find on the category editor page.