Magento Customization with Magento Marketplace

We are currently building an adult content provider website www.scarlettcontent.com. We have the theme already but need modifications made to the backend [login to view URL] 1) We are a content provider acting on behalf of studios selling their photos 2) Either ourselves or the individual studio needs the ability to upload their photo sets. We upload photo sets, not single images, these would need to be watermarked and available to preview, like product images but with watermark. Some sets can be up to 300 images and all need to be available for preview with a watermark 4) Release forms and documentation are contained with the images. These are private and not available for preview but must be included with the purchased download 5) When a customer purchases the images these must then be made available for download without watermark in the customers account along with the documentation 6) We also sell video. We make stills of the video so these would appear as the preview photos with watermark and when purchased the video file is available for download. 7) We also sell video+photos. The photos would be available as preview with watermark and when purchased both the video file and photos without watermark will be available to download in the customers account. 8) We handle all the transactions and pay the studios ourselves so all the studio needs to see is their sales. They won't be responsible for the actual sales transactions 9) To facilitate purchases we use Epoch so a payment gateway for them needs to be made (docs attached) 10) Certain aspects of the Webkul marketplace need to be turned off. We do all communication with the customers. The customer never deals directly with the studio. 11) There is no shipping. All items are digital downloads 12) As these are digital we are never out of stock so this kind of inventory is not needed *** please quote for this separate as it is not essential to begin with *** with Video upload is it possible for the site to display stills of the video without us having to do it manually offline. or maybe a better option is to have an upload field to display a 1 minute preview of the video with watermark. We could edit the 1 minute video clip offline, this wouldn't be a problem for us. Please feel free to get back with any questions