DDNS means Dynamic DNS, or in plain words, a system that follows the changes on your broadband router IP, so if the IP address of your router changes, the host associated to the DNS changes the IP too.

This is useful if you do not have a fix IP address (It can cost thousands $ per year) and you want to access from outside your network to remote access to computers, servers, CCTV cameras or or surveillance systems, etc.

Read more info about DDNS in Wikipedia

Just open the link we emailed once the host is validated and open the link inside your network (home or work). Here is an example:

Yes, you can using this trick:
Goto your domain hosting and add a new CNAME record like the following one

Yes, you can remove your host at the remove page.