Hey im new to blender!, im in love with the Pbr workflow but sadly… i dont know how to use the node setup for a few pbr materials like:
1)Ambient occlusion along with a diffuse texture
3)some maps have spectacular and roughness are they the same?, what is the node setup to connect them?
Complete Noob here would really appreciate it if someone helped me out 
If you are using cycles to render, you can generally ignore ambient occlusion, unless you have a special need (if you do use ambient occlusion, it won’t be PBR any more).
Bump is for more subtle surface details. Displacement can give more pronounced effects. Displacement changes the geometry at render time, so will likely use more memory off the bat, and generally works best with adaptive subdivision, which will consume even more memory.
As a general rule, leave specular alone (or if you must tweak, bump to .52, which some will say is more accurate. I have no view).
Use roughness to define haw sharp the reflections are. A roughness of 1 will give you a completely diffuse material (which is also not real world).