A web platform project with wordpress would be great and cheaper

Hello, my name is Javier and I would like to build a web site with the following characteristics:

a.- People can go to the website
b.- People can register and create login and password
c, I need a website or platform for many users.
c.- People must place duties
d.-People must share their duties in the website
e.- Text must be in spanish, I would send you the material
f.- I think a good option for cost issue would be with wordpress

This is my first email to you, what I need is:

1) What would be the price for a website or platform like mentioned above?
2) You can make a CRM right? I mean a customed Customer Relationship Manegement System, what would be the cost for something like this
3) I can make any digital system with you right? with wordpress I think it would be great because of costs
I need to know the prices or at leas a general idea.
I will wait your answer
Thank you!