Using SharePoint as a Knowledge Hub resource

Hi there, We are implementing new technology, which will change the way people work by improving and simplifying over 600 administrative processes. To ensure staff adopt the new technology and processes, face to face training will be carried and to support this, SharePoint will house all process (step by step guides) documentation.

The proposal is we will have 10+ business area sites which will house process documentation based on their business area and a Hub site which will pull everything together and (hopefully) separate it into two separate role type areas.  

The search functionality will be key and the user experience needs to be good. No doubt people with have the tech open on one screen and the process content open on the other screen, using both at the same time.

Will this in mind, can you help me with the below questions?

1. What would be better for the user to quickly find and use process content .... add content in a Word format,(using document libraries) or content on pages?

2. Should I be creating a SharePoint wiki for each business area? and can a wiki use both documents and pages?

3. Any advice on creating such a mammoth task? 

Hope this makes sense and thank you in advance.

I have loads of questions, think I may actually need to speak to someone for advice.