Additional functionality to osCommerce store PLUS a lot more future work

Hi, We have an up and running online store and want to make various changes to it : Change category navigation pane (currently it expands - we want it static) Add ability to refine search based on numerous categories Add category landing pages Add Google Checkout And other bits and pieces Once all this relevant functionality has been added to our LIVE site, we have a requirement to use this to start at least 3 more sites and will require graphics and template changes etc. We need very experienced professionals who will minimise risk and deliver a high quality solution on time and have clear communication channels. If we like your work we will continue to use you for the 3 other ecommerce sites and another 5 informational websites (possibly based on Joomla).