You definitely have the right attitude to your computer which should keep you fairly safe.
If you undo items one at a time and then have a problem, you have more of an idea what may have caused it so it is easy to fix.
You may get away with unchecking the whole lot if you know exactly what each item is, but I wouldn't really recommend that.
Stick around BleepingComputer, read about other's problems and how they were fixed, and you will soon be a guru.
A lot of us have learned that way. Good luck.