I should have a valid Tourist Visa after send de email asking for the exploratory visit?
No, you do not need to. What would you do if you have a VISA and your request for the visit is not approved. What you need to do first is to contact Manitoba Immigration Office to negotiate the exploratory visit. When contact them, make sure you attach your CV so that they can make a first judgment on your eligibility to MPNP. Once you have their OK to undertake the exploratory visit, then you can apply for a tourist or visitor VISA in order to travel. Note, however, that even if they approve your exploratory visit, it is your responsibility to have valid travel document to come to Canada as they will not help you in any way for that. I hope I answered your question appropriately. Bonne chance...