WordPress plugin Repository has a new plugin that lets you make website migration from one domain to another very easy. So next time you need migrating your WordPress site to a new domain, all you will be needing to do install and activate the plugin Automatic Domain Changer. After activation visit your admin area Dashboard -> Tools -> Change Domain (remember to keep a backup for safety).
There are plugins for adding NoFollow and DoFollow attribute to all external links in your WordPress site but this is what creates problem when you want to make certain link DoFollow or NoFollow and you get messed up because of some plugin activated in your site.
For adding an existing domain to your WordPress.Com blog. Follow these steps:
Step 1. Update your domain’s name servers to following: