Yes - the grey downy feathers mean that your bird is/was plucking... The feathers should be mauve, green and grey (towards the neck) and cover over all of his chest. Downy feathers should normally not be seen. The feathers may also never grow back fully - even if he stops plucking. Not that this matters a lot if the bird is otherwise healthy and happy...
What you are looking for is a full feather if he moults a feather and not a partial (half) feather that results from feather chewing. A full feather includes the calamus (the part that goes into the skin) - see
Anatomy and parts of a bird feather
Sprouts are very easy to make. Just rinse daily as suggested by chapala until you see little white roots - most likely in two or three days. Store them in the refridgerator for a few days as you use them and start another batch right away...