Is it true that the customer relationship management is a key and common tool for the sales and marketing strategy?

yes it   is true, the market exists thanks to the customer  and his demand , we have to  attract him , to satisfy   his requirements and needs, to establish customer loyalty  with him

Yes 

and it is reduce the marketing budget for the long term 

Yes, for sure its one of the most powerful ways to generate more revenues from your customers and retain them for a long time.

yes because good customer relationship is more important

yes for sure without the healthy relationship with your customer you cant market you product and for new customer you must be treat new customer like you are not new to him...

Yes... Although in many businesses you hardly receive a repeated sales, but still its one of the most important elements of a successful business strategy as it creates word of mouth...