You shouldn't mix dissimilar materials when recovering gold. It will cause problems.
Scrap karat jewelry needs to be inquarted before recovering the gold. If it is plated, then a different process is used. A different process is also used if it is layered (also called gold filled).
The process for the baseball cards would depend on whether they are cardboard or plastic. But trimming then down to just the gold part would be a good idea, either way.
It will be very difficult for you if you don't read the forum first. Since everything you asked is already thoroughly covered within the forum, and can be accessed using the search function at the top right of the page, those just getting started in refining are usually expected to try that first. And look over the various sections for the topics you want to learn, also.
Members are usually happy to answer questions about details of these processes, but are reluctant to write a whole book every time someone asks "how do I refine?" Know what I mean?
It's best to get at least a general idea of things first, so you will know what questions to ask.
