Now replacing a bathroom exhaust only seems hard but it’s really easy. The one I replaced in this video was an older style round one. And only had screws on the outside holding it in place. If you’re replacing a square one you’ll have to remove the guts (fan) still very easy and look for screws on the inside sides. These screws are holding the brackets that go from ceiling joist to joist.
If you just have a fan then you’ll only need a 2 wire. Meaning only one switch one power source. However a fan light combo you want to have two separate switches. In that case, you’ll need a 3 wire. Meaning two switches two power sources.