Hi Maureen and welcome to the forum,
Sounds like a pretty cool idea, so good luck with this.
To your questions, it doesn't matter how many other people are using the images on eBay, so long as you have permission to also use from the copyright holder. In this case that should be the supplier themselves, which shouldn't be a problem at all. From a marketing perspective, it's always a good idea to stand out from the crowd, so if at all possible, I would always advise for you to perhaps purchase a couple of items up front and take your own staged pics.
This has the added value of giving you a first hand idea on quality as well, you're not risking your customers as the test pigs (which is always risky)
In regards of finding the actual products, shoot an email to Link hidden: Login to view with your request in detail and the support team will do their best to find you some supplier leads for you to follow up with, if they are in fact unable to find any or our verified suppliers that are able to supply your requirements.