Hi Steve,
You'll have fun with Arduino, of the best kind.. where you keep learning new stuff. And doing hands-on development all the time you are in school is really important, in my opinion, to seeing where all those subjects fit in.
A few thoughts:
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Relays and controlling power with Arduino: http://arduino-info.wikispaces.com/ArduinoPower
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Android Phone/Tablet communications: You can talk to a "regular" Arduino if it has a Bluetooth or WiFi interface. See stuff like:
https://play.google.com/store/apps/details?id=name.antonsmirnov.android.arduinocommander&feature=search_result
and Google "Arduino Android" for lots more. -
Don't worry about the programming. Do learn about doing cool stuff with limited resources like I/O pins, memory, speed. Look at the Arduino Mega which has lots more pins and memory. See http://arduino-info.wikispaces.com/QuickRef
Lots of info on http://ArduinoInfo.Info Maybe start with http://arduino-info.wikispaces.com/Arduino-What-IS-it
And get some bunch of components and breadboard like a Starter Set from Adafruit, YourDuino, Sparkfun. See the hands-on "LEARN! ARDUINO - A HANDS-ON APPROACH" pages here: http://arduino-info.wikispaces.com/YourDuinoStarter
And you'll find many friendly enthusiasts like Nick and others here. As you become a good Engineer one of your best abilities will be to ask good questions. Often.