adding outdoor washer and dryer

I've read over the codes https://www.nfpa.org/NEC/About-the-NEC/Explore-the-2017-NEC?openpage=58&access=open

But still have some questions.

I plan on adding one 20A 115vac breaker and one 30A 230vac breaker. Then running the wires in two conduits thru the block wall from inside garage to the outside. then securing to wet rated surface mount boxes, one each for the 115vac and the 230vac electrical socket receptacles.

The boxes and enclosed covers will be wet outdoor rated.

The receptacles will be GFCI.

I believe the codes said I needed a cutoff outside the house. Why?

When I read the codes a few years ago, I though I read mention of 4 prong required for the 230vac and I think there was also instructions on how to hook up a 4 conductor cord to the older 3 terminal dryers, but i cant find that now.

Any advice will be appreciated.

paul