Should I be creating a Multisite for what I want to do here??

This is for a website design business. I want to have a page on the site where potential customers can see examples of all the different website designs I can build for them.

That page will have thumbnail images of approximately 50 different website designs. When a visitor clicks a thumbnail image a demo of that site will open as a popup (or whatever it’s called) on the same page (like Themify did here https://themify.me/themes) or the demo site could open in a new browser tab.

4 QUESTIONS PLEASE:

1) In order for all 50 of the different site design examples to be on one domain, would each thumbnail image of the design be linked to a different subdomain so that site design example #1 would to to 1design.mysite.com or a separate subdirectory like mysite.com/1design?

2) If so, what are the advantages and disadvantages of creating a new subdomain for each website design example verses creating a new subdirectory for each – and vice versa? Again, there will be 50 different website design examples on one domain so which would be easier and faster – subdomains or subdirectories?

3) I have never created a multsite before so just to make sure I’m going in the right direction… Does what I want to do here require a Multisite or is there a better way?

4) Lastly, how would you have the demo sites open as a “popup” on the same page like Themify did here https://themify.me/themes ?

Thank you! ??