Replace a Magento Theme and more

My website is https://fitnessculture.gr and I would like some one to handle these requests.

1) Update to the latest Magento 1.9.3.x or go directly to Magento 2 (Have not decide yet need your opinion_
2) Replace Theme with a new one (New theme will be provided for Magento 1 or Magento 2) and customise it appropriately
3) Create B2B Site View which will be available only for loged in customers (and add one more delivery option)
4) Create XML Feed (ready for e commence market place)
5) Keep the multi language 2 stores
6) Check for responsiveness
7) Ensure that the website will continue working with the bank API as it accepts payments through credit cards
8) Keep if possible the hero menu with the images
9) SEO optimisation for the current products