/blog, where did it go?

Hi, Im setting up a site on my multisite network. The site, once finished, will become the main site within the network.
The current main site url is: http://my domain.com/
The site in development is: http://my domain.com/development/

I'm at the point where I'm choosing my permalink structure. I want to match the structure of the current main site which is http://my domain/blog/date/category/postname.
Now when I try to match the permalink structures I see this in this in settings > permalinks for their respective sites:

http://my-domain.com/blog /%year%/%category%/%postname%/
http://my-domain.com/development /%year%/%category%/%postname%/

My question is, when I move my development site to the main site position does the development sites permalinks transform to http://my-domain.comg/blog /%year%/%category%/%postname%/ ? Does the old main site become http://my-domain.com/what-ever/?

Now my third question is, what is the current best practice for making such a move, sub site becoming the main site in the network?

I hope that I have made this clear. Thanks, Sam