I use the gel form of Clindamycin and love it. I only have to use it two or three times a week now b/c I'm pretty much clear from B5.
I didn't moisturize. There was no need. The clindamycin did not make my skin dry at all. All of the other products I tried did.
Sometimes I wear it under make up. In this case, yes, I moisturize after I apply it. I wait about 10 minutes to allow it to soak in.