Online Shopping Portal

Want to improve our web portal with Zen Cart, made by us, for our client, and replace it with with more modern Shopping Cart ( like Joomla Virtumart / Magento / Presta cart etc. choose the one which you are most comfortable with. Technology no bar.) with 400+ products with PayPal integration and having built in, self-sustaining, self-compliant SEO, SEM features (google analytics etc., properly structured with meta data picked up from product data). The store should be capable of being updated using a single excel/ .csv sheet reliably without losing any data (Tomato Cart update requires you to delete all products before uploading a new set. This solution is NOT ACCEPTABLE) and without throwing up errors. We will be doing this multiple times even after the project has been completed and the full payment has been made. THIS SHOULD ALWAYS WORK. A system to eliminate copy-paste while printing orders according to the format we provide (something like MS Word mail-merge but automatic). Not even a single copy paste should be required as long as the address during checkout was correct. Use connections to the database for doing this (or any other technique you are comfortable with). A complete ready-to-print PDF being mailed to the sales email address after order completion is the minimum acceptable solution. Anything better is bonus. It should also create daily inventory deficit list according to sales made. Reliable and verifiable, complete transfer of traffic from 2 separate domains to this one particular one (A--> New A, B--> New A) List of products will be provided in the form of an excel sheet to the developer with all related data (description in html, category(s), price, weight of items) and should all get updated in 1 shot so charge-per-product bids will not be entertained. Bid only if you already have good experience in building an integrated solution for Online Shopping. Finally, Freelancer shall handover the controls/ passwords and delete all data provided from our side after completion of project. Total confidentiality is expected. We might need more features implemented in the future in a separate project, so desktop app development is an added bonus, if you want to get re-hired. If you can implement those features in a web-based environment, it is even better.