Pantone colours or CMYK for a 1 colour t-shirt print?

I designed and sent a 1 colour t-shirt to the client for the final review and I used black colour on white shirt and white colour on black shirts as i don't know what colour is going to choose yet. The client didn't give me any specification on what type of colour process wants and what kind of shirt is printing i.e.American Apparel etc.. I don't know as well if he'll use Plastisol, Light Plastisol or Discharge type. Some of these point will be clarified in the next few days, but i need to ask some questions regarding Colours and printing as my client might don't have a clue of all these specifications.

1. 
   

   Should i use a Pantone Spot Colour or CMYK 4 Process Colour?

   
   


2. 
   
   

   What's the difference in terms of Printing quality on T-Shirts if Spot Colour instead of CMYK?

   
   


3. 
   

   Should i make the colour separation in both cases, when if using Pantone Colour or CMYK and only 1 colour (white or black) for the t-shirt?

   
   
   
   
   4. 
      

      In case the design is printed in Black Colour on White shirts do you suggest to use a Rich Black?

      
      
   
   
   5. 
      

      Can i use the Rich Black as Spot colour only or as a Process Colour as well?

      
      
      
   
   
   
   

Thanks in advance for your support.