Hi Jojoe, that's good growing of your leaf cuttings!
I think it takes awhile for cuttings to grow their roots depending on the season you took them. That's what I see here in my garden. They grow faster when weather is heading warmer or still warm, that's why I prefer to take mine around spring or maybe early fall. I also try to observe when their active growing season, some are actively growing in summer than winter or vice versa.
Pumice and sand helps in drainage. I just use ordinary cactus soil and add some more perlite to make it drain faster. Recently I have been using also some bonsai mix , kanuma and akadama, and it works good too.
It is up to you if you want to plant them as one set or mixed with other succulents, just group it with similar watering requirements. Some succulents have high light requirements, some like shade, so if it seems they are going lanky it wants more light..on the flipside, if it is bleaching out, give them shade.
