OMG of course!! From Amazon:
Arduino and Pi will both be fine. Pi has its own OS, so no issue, and the Arduino sketchpad program looks like it can run on Mac.
I'd recommend looking online for guides, which usually have parts lists you can follow.
Likewise, I like books. O'Reilly and Packt seem to have some decent "project" books that gives parts and ideas/guides. Some seem to be geared to students and can go into why some components are used. For instance, if you've never had an EE class, you may not know why you'd need a pull-up or pull-down resistor.
Looking online, some that don't look bad: https://www.amazon.com/Learn-Robotics-Programming-autonomous-Raspberry/dp/1789340748/
https://www.amazon.com/Arduino-Workshop-Hands-Introduction-Projects/dp/1593274483/
You can find plenty of others if you look based on what you want to go with. I don't think it's a bad idea to work with both a Pi and something like an Arduino. Save the hassle of dealing with the wifi header (an expansion board specializing in a given task, they stack on top of each other but I remember there being some headaches between some header boards) for an Arduino by using the native internet connection of a Pi while learning more about serial communication. You'll probably need/want to use a motor controller header.
Worst case scenario, I believe I remember hearing things like https://www.adafruit.com/product/749 (an Arduino BOEbot starter kit) aren't bad starter kits. Play around with it, or a kit like it, and then start messing around with adding sensors you want since you'd already have the platform.