Hi AMMUT,
I work as a systems admin, so having a home lab is invaluable to me. It provides a great opportunity to learn and provides an environment I can play about in without screwing up a live environment. Snapshots let me tinker away without worry.
Saying that, if the DC goes down, or DHCP or DNS screws up, family can end up unable to get online, so be sure to set backup DNS server settings and static IPs on each family workstation!
Setting up is easy. I follow the technet guides and have no problems. Just be sure to follow best practices.
http://social.technet.microsoft.com...-your-first-domain-controller-on-2012-r2.aspx
Exchange is great. Having Enterprise email for my family is actually quite useful. We use shared calendars to good effect.
To begin with though get yourself a static IP from your ISP if possible. Otherwise you will have to setup MX records to a DynDNS type service. This should work, but if your updater app fails then you'll end up loosing emails without a backup MX in place.
Also perhaps start with a secondary external domain on the emails until you are happy its working before moving your main domain over.
Good Luck!