Template and Theme Selection

I am a newbie to WP. I have however, worked with HTML and Joomla over the past years (novice in both areas). I am asking for help and direction with theme/template selection. If you have a preference where to obtain the best themes/templates relative to my business requirements, please let me know. I need to build two separate websites with the following high level business requirements:

A. Ability to support purchasing of products with payment processing.
B. Secure portal for each customer logon.
C. Ability to support on-site video clips for marketing.
D. Ability to support SEO.
E. Ability to support links and all major social sites.
F. Contact form with email feedback (the usual stuff).

Thank you,
James