Yes, the crown is necessary to finish your stack of barristers. Without a crown, you will be able to see into the top of your shelf unit. The shelf units don't have their own top panel.
No, if you prefer to have your shelf units on the floor, you do not need to order a base.
Yes, just send us an email requesting the finish color numbers you would like to see along with your address.
You shouldn't stack more than 9 shelves high, and we recommend anchoring units over 4 high to the wall.
Yes, the "Inside Dimensions" shown are accounting for the door being open/receded into the top of the shelf unit, and with the door being closed in front.