For toys, it depends on the bird. Try everything and see what they play with. Try again in a few months, because they change their minds.
When my bird molts I start seeing down feathers around the cage. Then pin feathers on the head as the new ones come in. I see a few larger feathers, but not many.
Unless your bird is too fat or skinny, they should always weigh about the same. A sudden weight loss is often the first sign of illness in birds, so daily weight checks are a good idea.
Introduce new food by eating (or pretending to eat) it yourself. Make a big deal about how good it is, and when they come close, offer some. The Parrot Wizard has a video at
http://trainedparrot.com/New_Foods/