we(2) adults will be travelling from Gare Du Nord to Clamart by train. The ratp route planner shows the following route:
Gare DU nord --> Montparnasse-Bienvenue ( metro )
Gare Montparnasse --> Clamart ( T)
Clamart is in metro zone 2 so we should be able to use 2 t+ tickets for this journey right?
Also i read on a blog that it is not a good idea to purchase Paris visite pass for 5 days(Friday - tuesday) from the ticket machine because you dont get the card. Is this true?
Since you're crossing from Zone 1 to Zone 2, you actually need a point-to-point ticket, which is priced for start / end stations, costing 2.80€ for Gare du Nord - Clamart. So buy a Billet Origin-Destination / RER ticket for Gare du Nord to Clamart and use it for the transfer at Montparnasse
The Paris Visite, bought from a Paris Metro ticket vending machine, won't give you the little tourist card which lists some of the discounts, but that little card isn't what entitles you to discounts, it's the validated Paris Visite ticket itself. You can download a PDF of the latest discounts from RATP.