Hi Chantal and welcome to the forum,
Don't worry about being overwhelmed, it's a lot to take in when you're just starting out in online sales, but that's why were here. Any questions at all, just give us a shout out and well get you some advice.
A few points to cover for you, but I think it's best we start by clearly defining the difference between Wholesale and Dropshipping as you seem to be using both terms as a single entity, which they aren't. You can read about the different supply methods on the thread below to get a much better understanding. .
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In relation to your questions. Most suppliers will provide you with product images, however just check with your actual supplier to confirm what they provide for you to be 100% sure.
When you're ready to start selling you have to open an account with the supplier/suppliers of your choice. You can find those that Dropship specifically in our directory by using the search interface to narrow your results down to just Dropshippers only.