How do I know when sweetcorn (and tomatoes) are ready?

[geogteach]

Sweetcorn just not really sure when to pick.
The tomatoes i'll admit have not been greatly cared for but there are a fair few there they are just all green, I assume thats down to lack of sun, do I just leave them and hope or bring them in to ripen on the window sill?
While i'm at it I also have a pumkin when do I pick that and can I then store it for halloween?

Sweetcorn... the fluffy bit at the tip is brown.
Tomatoes... should be red, but we always cave in, pick early, and try to ripen on the window sill.
Never grown a pumpkin in my life.