If PayPal decide the claim in your favour, you will be required to pay for the return postage (and supply the proof of postage) but they can only refund the the original payment (in full), so they don't reimburse for the return postage. Also, once a dispute has been escalated to a claim, no one can participate (i.e. the only time buyer or seller can communicate and/or provide evidence to support their claim is when the dispute is open but not escalated to a claim, escalating means PayPal take over and decide based on the evidence that has been provided).
Regarding everything else, others may disagree, but for me personally a seller should provide a full and accurate description of goods, including any flaws, both visually and verbally (meaning it should be clear to anyone who looks at the photos and/or reads the description, what they condition of the items are). And it's not ok to use a different brand name to describe an item, no matter where it was bought from. eBay have even clarified this in their policies, and don't allow a seller use parent companies in titles or descriptions (a good example is Veronika Maine, which is a division of Cue. You can use Veronika Maine in the title / description, but not Cue - there are some exceptions, like if the tag says XXXX brand by XXXX company).
Feedback, however, is entirely up to you. I would take into consideration how the issue had to be resolved when deciding on the feedback to leave, though, and I definitely wouldn't appreciate emails the nature of which you have described.
Just for future reference, after November 1st, you will have the option to dispute transactions like this via eBay instead, and if a case is found in your favour, the return postage will be the responsibility of the seller.
Edited to add: Don't mention the dispute in your feedback, as it can be grounds for removal. If you want to refer to it, you can say something like "would not voluntarily resolve".
