An S Curl is a texturizer!!! Like a Jheri curl, but not set on rollers. It just loosens your texture.
And yes you can wash your hair!! Don't be goin around not cleaning your hair. Other than using products made for a curl, you can do what you did with your regular curls. You can actually probably use regular products too. I don't see why they wouldn't work. Shea moisture and what not.
You can also cowash if you don't use non CG products.