Yep, once the mildew hits the plant can no longer draw nourishment from the leaves,,pull them and store if hard(wipe with mild bleach solution)if you have very tiny ones use them as courgettes, even the really small ones are good this way.
Re the scabs. Scab is a bad disease of squash, cukes, melons etc the areas fast become sunken and open and the fruit starts to ooze.. nothing to do but chuck them..but.................... don't mistake what you describe as a scab with a bumpy warty lump. This is common to many types of winter squash and is part of their beauty. A picture would be good and I can tell you exactly what you have so panic not.
XX Jeannnine
