@BuckeyeNation27
It may seem like a lot, but this is a pretty easy switch over. The only electrical I wouldn't get into is any old knob and tube but since it's hooked up to an existing exhaust you won't have any problem....when you disconnect your wiring, just keep an eye on the poles/where the wires are hooked up. The guide with your new fan should make it super easy....I personally always recommend putting your old fan on before you disconnect and then switching the breaker, safety first there
And yes - cut a square out going about halfway to your joists/studs. No need to precut your new vent hole - do you have a drywall knife? Even if not, any box cutter will do just fine.
Use something (marker, wifes lipstick, anything) to put on top of the vent that will need to be fit onto the drywall. Press it up against there so you know the exact size of your cut.
Also - if this is a second floor or a ranch, make sure to wear a mask when you cut your drywall hole....depending on the age of your home or when/who installed the old vent, when you cut that other drywall the last thing you want is to inhale some lovely insulation!
If your ceiling is textured or anything let me know in case you need to match the new with the existing. Lastly, once installed, run some hot water in the shower and keep the door closed while it runs....after 5 minutes, if you have access...go check the attic and check for moisture to make sure the fittings are right. Last thing you want is that sucker spitting moist air and winding up with a mold farm a year later!