Add features to my WordPress Online store.

I have a WordPress site with theme forest theme (Crunch Press Book Store). I would like majority backend development done. Minor frontend work. The work details are as follows: 1. ERP DB integration. Stock count updated twice daily for all products by enquiring on the ERP DB or looking at CSV file generated from ERP DB twice daily. 2. Search feature needs to be updated, so that it is more extensive in its search. Also Advanced search feature needs to be added, where parameters will be selected by the website customer. 3. Payment gateway integration (PayU or CCAvenue). 4. Shipping providers portal integration (provider TBD) 5. Creating separate stores based on countries. Not all Products available in a single country. 6. First time customer adds an item to his basket, the customer is asked for Shipping address. Based on the selection, the country specific store gets displayed. 7. Product description page needs to be tailored, showing specific dynamic content in specific places. 8. SEO optimization 9. Existing Blog (Blogger) needs to be migrated to this new wordpress website 10. Migration of products (about 4000) and users (about 2000) from existing MS-SQL DB to the new WordPress mySql DB. 11. Add option of adding product to Wishlist. 12. Based on customers browser history (cookies), show the customer matching suggested products. This work will require office visits and possibly on-site development. Link to current test installation can be provided on request.