-How's Naruto able to communicate with the Bijuus and use all their techniques?-

[Darkas]

So then why don't they speak to Madara?

I don't think they want to, they despise him and any little thing Madara may take for granted might cost his life.

 

[itachi uchiha fiance]

The Biju are made of chakra...what they gave to Naruto is actually a portion of themselves; The Jubi is comprised of the Biju and Naruto as a host there by has access to their power [chakra] and is capable of conversing with what is sealed within him. 'Pseudo' implies that his reflection falls short of the original image which is true as the larger portions of the the Biju are sealed within Madara.​

this .........
i agree with u and nice explanation