Magento Store and Configuration fix only

Hi, I have two fixes to be done in my existing Magento Website. 1. I installed a etheme, then I lost access to configuration page. All i get is only this error code. Fatal error: Class 'Etheme_Dresscodeconfig_Block_Adminhtml_System_Config_Form_Field_Customfieldfont' not found in /home/public_html/app/code/core/Mage/Core/Model/[login to view URL] on line 590 2. In this same portal. I need multi-store to be enabled as Addon Domain. - I followed this tutorial (crucialwebhost(dot)com/kb/how-to-setup-multiple-magento-stores/#url-structure), it works but the issue is creating symbolic link to the original magento directories not working properly. Only if i create a copy of the necessary folders to the addon domains - website works. I don't want to duplicate files in that way... Kindly do a good job and i am really looking for a long-time contractor to configure and set up additional magento stores regularly. Also I require frequent magento works as a part of my ecommerce portal