When you follow someone, the default setting is automatically set to go with the title of the first blog you posted. An easy way to change this is: when you select "follow" from another page a screen will come up that has your picture and blog URL, just delete the URL and enter the one you want.
You can also use the same Ad codes on all your blogs if you choose to. Just use the copy/paste.
To get multiple blogs on one profile: from the main menu select "Create Blog" enter the information for your new blog using the same email and password as your old blog. Now when you are on the "Dashboard" screen you will see a list of all blogs you have created and can work with them separately. This makes it easy to keep up with multiple blogs at one time.