Lyn, I would think that your "fast draining" soil mix that you mentioned should be good for repotting the 4 in pots. Are you planting into ground or into containers? Same soil should do for them.
Regarding separating the offsets: Do you want to have that colony look/formation to them?...If so, then repot into larger container/ground so they will grow into that shape making sure that chicks have contact with the soil if possible so that they can root.
If you want more specimens in different pots or in different area in the ground to spread that particular semp variety, then separate the chicks off mother and plant elsewhere.
