Ebay store and listing template

We are an established eBay seller for 10 'ish years selling mens underwear, sports and leisurewear which we import from all over the globe to the UK and sell worldwide on our eBay site. We do currently have a web presence (built on a zencart) but again with the number of changes by google to the search rankings I am planning to close down this store to concentrate entirely on eBay and possibly Amazon. I use a basic template for listings at the moment but is not compliant to eBay current standards (with both active content and external links) and, so I'm told by eBay, will be removed in January. The project will be to completely update our eBay site including store front and offer us a listing template to work from. The site must be responsive so that it works on desktop, tablet, and mobile and must work in the eBay app. Of course, the shop and listing template must be to current eBay guidelines. For the listing template it should include tabbed information for About Us, Payment, Delivery & Returns, Feedback, Sizing Guide. The listing template will also need to be able to cross sell to other similar products from the shop (either at random or selected at time of the listing). We do currently, within our template have links to our products and brands within the eBay store and I would like to keep that if its possible. Fixed images (i.e. not clickable to enlarge) are contained on our template to show additional images to the eBay listing and these are hosted on onedrive - this again I would like to keep if possible. I have a logo banner which can be used although some adaptions may need to be made to it to fit with the shop and template. Within the cost of the project should be my ability to make changes to make the shop and template appealing to the market we are aiming at.