I think this is probably what you're looking for:
https://www.edexcel.com/migrationdocuments/GCSE%20from%202011/UG034969_GCSE_Lin_AddSci_Issue_3.pdfYou'll see there that there's a controlled assessment involved, which is a form of coursework.
As for relative ease of the qualification, I'd suggest that you shouldn't be concerned about that - firstly, it's not the reason why you should make the decision about choosing one course over another, and secondly it's going to be a largely subjective measure anyway.
I'll leave your other questions for others to pick up, as I'm not in a position to give a reliable answer to those. Best of luck with getting this sorted.