If you have lots of plants (fake are fine) and hiding holes, they should be fine in such a big tank. But you may want to QT them in individual tanks for a week just so they can adjust from their long overseas trip.
That's a tricky one! If they are from the same breeder, you could put them into the tank after a week QT to let them calm down from the trip. The other girls would need to QT for a week as well, and then you could need to take everyone out of the tank and re intoduce them all into the tank after you have changed it up. New territories. I was lucky that my 5 girls got along great from day one.