Alternative to FaceTime or iMessages to communicate with Android devices?
Well, you cannot use iMessage or FaceTime with non-Apple devices.  With iMessage on the iPhone, the phone will switch to SMS messages when contacting non-iPhone users, but that's it.

Fortunately, there are alternatives to FaceTime and iMessage that are cross-platform.

Alternatives to FaceTime:


Skype (Mac, PC, iPhone, Android, Windows Phone)
Tango (PC, iPhone, Android, Windows Phone)


Alternatives to iMessage:


Kik (iPhone, Android, Windows Phone, BlackBerry)
Facebook Messenger (Works on pretty much anything with a web browser)