Answer: Yes. You should reaffirm with the attorney that what you are telling him or her is subject to the attorney-client privilege. You should make sure that the attorney understands that a privilege exists even if no case is filed. A good attorney will have no problem with this request.
Answer: Many potential whistleblowers contact attorneys just to get an independent perspective on what they are seeing. Sometimes, the would-be whistleblower will decide to do nothing. Sometimes, the would-be whistleblower will go forward with a different attorney. Sometimes, the would-be whistleblower will take some time to think about his or her options. Contacting an attorney requires nothing more from you than a conversation!