Hi there. I've just started using the site, and I'm not sure of all the things I am able to do. I can see that some people have a lot of things that they want from my trade list (common, uncommons, etc). Is there a way to add the whole list automatically to the trade then remove things one by one instead of adding all the items individually?

Unfortunately this isn't an option yet, but it has been requested a few times before so it's on the to-do list. :)

+1.

Could be initially implemented as a checkbox in the New Trade screen: |_| Add matching cards to trade (would add matching cards from both traders).

I don't think this goes far enough as wishlists may change during a trade. I think there should be an indicator for cards in a trade that are not on the trader's wishlist. And also a fast way to add cards that match, perhaps add them to the trade but have them greyed-out and not count until you click on them.