A: I dont see that as a good solution, your clients will probably want their own domain? And each project is connected to 1 domain.

But theoretically that is possible what you have said, those would be pages. So each clientwebsite, would be 1 page?

Also you can create a main page for example:
client1, and then inside of that you can create pages such as about, contact, etc,
and links would be:

website.com/client1/about

But again, I am not sure why would someone do it like this, but if it works for you, works for us :)