I can't help you directly with your questions about the camera except to say that it's not at all unusual for cameras of this vintage to need new light seals. It shouldn't be an expensive job and depending upon what you paid for the camera shouldn't necessarily be a deal-breaker. However, considering the description and the condition you describe, you may want to return it to the seller. In any case, you should contact the seller regarding the discrepancies.
Ebay is a crap shoot. It can work very well if you know the seller, are very familiar with the goods involved, get lucky - or all three. If you're starting out in a realm in which you're unfamiliar, you're usually better off going to a reputable retailer who will stand behind his product.