If you plug the cable into your PC in a USB port, the photos should automatically transfer to you PC. I would have folder ready to store your ebay photos, so that you can quickly find them. You will get a prompt, asking you what you want to do once the PC recognises your phone. I'm unsure how it would work on an ipad. I have a Samsung phone and the charging cable can be used, no need to buy a separate cable.
The only problem I have found is my phone keeps locking if I go away and leave them downloading, so I have to keep unlocking it.
You can also do that to get rid of all your sent Whatsapp photos , rather than clear them on your phone, if you run out of memory.
You could set up Bluetooth on your phone and on your computer that way the photos could be transferred wirelessly between the two. Once you have enabled Bluetooth on both it’s fairly straightforward - just follow the prompts. Hope that helps.