1) Valdis isn't psychic, but she can speak directly into people's minds while in hound form and pick up on their surface thoughts, but she can't dig into thoughts or memories in this manner.

2/3) Valdis isn't immune, or more susceptible than others, but unless Penny wants to have a conversation with a seven headed serpent, he might not want to try.

4) That said, it still might be fun. For us anyway.