Actually, Ebay always needed your personal information. Do they need more now? If so, I haven't really noticed. But that's one thing that they did need a lot of info for, to make sure you aren't making fake accounts. Honestly, that is the only thing I agree with. It helps keep the community legit.
However, you asked if this can make you run into trouble. Well, only if something weird happens and your account gets banned. You will never ever be able to make another account. Even if the ban was a mistake that had nothing to do with you. So that's the only kind of trouble. But if you are thinking of identity theft I think we are safe there (did cispa pass?)
They need a credit card cause they like to pretend that they are entirely separate from Paypal and can't talk to them (which is utter nonsense - it's just a way to force you to run in circles).
They need your credit card so if you decide to stop paying fees, you can still be charged. Also, for buyer's claims. Ebay will refund a buyer without any say from you.
Without looking up the exact percentages I can tell you that with Ebay & Paypal together. The fees for a $10 item w/ free shipping are around $2.50 (rough estimate).
Remember, you have to pay fees on the shipping as well.
Lots of newbies screw themselves on Ebay. They have way too high expectations and end up paying to ship an item to a buyer. They achieve this by under guessing shipping, not factoring the fees, nor factoring in the materials and time, and finally not factoring in the fact that things don't really get bid up anymore.
So if you start something at $0.99 it's very likely it will end at $0.99. Start your items at what you want them to end.
It's just some things to think about. Are you thinking of selling ponies or do you have other items?