Try rotating the whorl in the opposite direction (clockwise) after spraying it with WD-40 to loosen the gunk in there.
The metal thing on top of the table is how you control the tension. You should be able to loosen the wing nut to tilt the Mother of All (MoA) towards and away from the drive wheel.
Yes, you can put on your own drive band. A thinner cotton string (like kite string) that has been waxed with beeswax should work, or even a cotton yarn.
Place your MoA about midway point in tensioning. Have someone hold one end of your drive band above the whorl (or tie it on to the maiden). Wrap the band over and around the drive wheel, back to the whorl, back over the drive wheel, back over the bobbin whorl. Tie off.
The disconnect may or may not cause problems with the action of the treadle.
Make sure clean all the gunk from the flyer and the drive wheel shaft (WD-40 is great for doing this) and re oiling EVERYTHING. The flyer shaft, the leathers that hold the flyer on, the drive wheel shaft.