Changing Menu Names
Changing menu names is very simple. You just go to the dashboard and select pages. Then, select a page, change the name, and click update.
Changing Menu Order
Changing menu order is a little more difficult to do.
To change the order,
1) Login to Wordpress admin
2) Select Pages
3) Put a number in the order. For example, your home page could be number 0 or number 1. If it was number 1, the next page would be number 2, and so on.
If new pages are added, yo just do another order shuffle.
All submenu pages for the parent pages will remain intact.