I think the silver pencil markings will come out in the wash. I would be more worried about the red or the blue bleeding.
Do you have any scraps of the red (and the other fabrics) that you could test for bleeding? You may luck out and there may be no bleeding at all. However, if either of the dark colors bleeds, you will have to take a lot of precautions when you wash it. If you don't have any fabric scraps to test, I would at least dampen a white cloth and rub the red and the blue to see if any dye transfers.
Whether the test fabric bleeds or not, I would recommend a first washing in Synthrapol (suspends unset dye particles in water so they can rinse away). If the test does show bleeding, you need to wash with Synthrapol in a machine that holds a *lot* of water (to give more opportunity for unset dye particles to stay suspended in the water).
p.s. The quilt is *gorgeous*!!!