Confusion around Host Named Site Collections, Host Header Web Application and MySite host

Hello

I am confused about the best practice to set up web applications in a corporate environment.

We have got a Three Tier SharePoint 2013 platform setup. We are confused about the best practice of using HNSC, Host header web applications and where to host MySite Host.

Based on our requirements, We planned for

1. Web Application without Host Header on port 80. we are planning to use this web application to host HNSC. This is for one part of the group which wants to have their own site for each of its location.
2. Web Application with Host Header (http://websiteB.company.com) on port 80. I think because we have used Host Header in Web site level we can't host HNSC in this web application. This is other part of the company which wants to have only one site for all of its locations.
3. MySite host web application with Host Header(http://mysite.company.com) on port 80. 
4. As you can see all the web applications are on port 80 but different application pools

• Can any one see any problem with the above set up. 
• We are planning to make the sites external, do you think will i hit any problems with this set up.
• how about app development for this set up.
• Is there any problem having multiple and my site host web applications on port 80.
• Any other issues which i can't see now.

Thanks, please help me with this confusion

Thanks very much

sharedata