What are the most difficult parts of BLC?

if you are of average intelligence and apply yourself, you should have no problem with BLC as long as you can pass PT. I had guys that were dumb as rocks in my PLDC class and they still passed. It's not rocket science.

Your bonus is not tied to your PME. You will have other issues result if you end up failing BLC, though.

As others have said, BLC is not hard. Once you make Height & Weight and pass your ACFT (if they give a test) you're golden. I went to WLC in 2009, and the toughest thing academically was giving a class on an assigned subject. I put together a powerpoint presentation within 2 hours.

You should be fine. D & C is not as hard as it looks. At ALC, we were told we would have 5 days to prepare for D & C testing. The next morning we were tested; everyone did fine. If you do your D &C in a parking lot, use the parking space lines as guides from which to base your formation. Each space is usually about 3 paces. So align yourself where the lines cross, form the platoon/squad on the next parking space line, and there will be a line down the middle to center upon.

Do your best, and take notes where you need to. Help your classmates. You'll do fine.