When I did a search for "Perry Marshall" I see an ad saying "Perry Marshall Exposed, Learn what he doesn't want you to know" or something like that. Is this allowed? Can I bid for the keyword "amazon" then say "Amazing is more expensive than us"?
I'm no IP lawyer but have had experience in the field, and I would say that would qualify as misuse of a trademark.
Is "Penny Marshall" trademarked? Or is it just the personal name of an actress/director? Amazon would most likely have their lawyers send you a a cease&desist for using their "mark" in advertising. They have whole departments that keep watch on this sort of thing.
You would need to do a Trademark search in the relevant country registration office. You could do a madrid search as well.
Are you allowed to bid on the term without mentioning them in the advert? For a better example of what I'm talking about, search for "wealthy affiliate". The results are full of "wealthy affiliate is a scam" type of things.
Yes, you can bid on competitions keywords and use them in your ads. Look around and you'll see this done in advertising everywhere. Remember the "Pepsi Challenge"?