1. You can set up the ranks to change automatically according to the number of posts. Go to Admin Panel -> User Admin -> Ranks. Press the button that says Add New Rank and type the desired rank title and the number of posts. You can also add a rank image if you want. Make sure that the rank does not have a special status. You can make special status ranks and assign them individually for moderators, administratos, etc.
2. To make somebody admin go to Admin Panel -> User Admin -> Permissions. Type in the name of the user that will be assigned admin permissions and click Look Up User. Then change the drop down menu at the upper left corner to read Administrator instead of User. However, making a second admin is strongly not recommended, unless you fully trust the user.