Just a couple off the top of my head:
Did you turn off imessage on your iPhone?
Is this your first android phone?
If so, don't expect it to work like an iPhone. The entire OS philosophy is different--not at all a bad thing!
When I get a new phone, I just dig in and start tinkering. That's how you discover the awesome things your phone can do!!! One of the best things about android is, if there is something you don't like, you can almost always change it!! Hope you enjoy your device!