Salesperson at my local JB showed me this today, I believe I have all the correct details
Can be an existing customer, just has to be a new service
Max 1 per customer
Update 24 Oct 9:40am: Judging by this comment, the deal was changed around 8am this morning to require the purchase of a device. Deal expiry set to 8am.
@haemolysis: The 12 month contract I sign up to, JB did a "hard" enquiry. And yeah like koOl said below, that's most likely because it's a postpaid thing. My guess is that this will also be a hard enquiry given you don't pay the $75 before the plan starts (for these so called Telstra prepaid plans, the bill actual comes to you a few days after you start your service).