Mealybugs are scale insects without the hard shell the scales usually have so control is about the same. Insecticidal soap sprays will help, superior oil also can help. It is unlkely you will find any on the glass and walls of the Atrium since these wee buggers need to be on plants to live.

Here is a link that might be useful: Mealybugs

I think the white chip/landscape rock is a wonderful idea for your fluffy friend. If you would like a little variety in your ground cover, here are a few ideas that have worked for me. You could use them slightly under the ground cover of your choice.
1) Chicken wire spread across the surface of soil. I'm sure you could cover it with a little bit of soil or decorative mulch to hide the wire. My kitty didn't want to dig with the wire in the way.
2) Another immediately effective idea I used was plastic forks broken in half and pushed to the the soil line with the tines up. I used plenty of them.
3) Tin foil is less effective, but a good temporary solution until you get the supplies you need for other ideas. Spread over the soil, the sound was enough to spook my fluff ball away. We actually, left this temporary solution on one plant so long that when we removed it, he didn't even consider bothering that plant again.

Oh, for the transporting the ficus, I was thinking putting a chair cover (like the kind for moving) over the leaves might help keep the mealybug escapees contained. I've purchased the chair covers for a few dollars at Staples. They are with the mattress covers. It would look like a huge garbage bag.

Good luck and I am jealous of the atrium.

mobenchain, you have a formidable problem but it can be solved. Think Eliminate, Reduce, Protect and finally, Control; not as isolated items but as an integrated plan.
By removing some host plants you have already done some of the first two.
Consider ways of doing the same on the remaining plants, like pruning the most affected parts. Note that the primary purpose of this pruning is for pest control and it may clash with the aesthetics. You will have to make that choice. Take the plants outside and hose off (protect the soil against the heavy watering). A hose-end shutoff, opened just enough to give a thin, forceful jet will knock mealy bugs out of leaf axils without dislodging too many leaves. If the plant is too tender for this treatment, use a sponge to do the job. You will be using water volume, rather than pressure to get rid of the pest.
I cannot think of practisable protection devices in your situation but think of how you can use sticky traps, netting covers and barriers to prevent reinfestation.
Control methods offer the best hope. These can be mechanical like glue traps and sticky (on the OUTSIDE only) bands on the stems near ground level. Cultural controls embrace watering and can include manipulation of the environment. Can you lower the temperature in this space long enough to simulate winter? Painting the room has possibilities. A newly painted room, locked up for a week or so may make the air toxic to small insects-I do not know.
Biological methods will include elimination of ants, introduction of lady bugs, (I do not know how this will work with that painting operation) and others which I cannot recall right now.
If your philosophy includes the use of chemicals, I would recommend a pyrethrin (not pyrethroid) formulation. The latter are tweaked to add properties like residual- the same property for which other chemicals were withdrawn.
Scales pose special challenges. Even when they are dead they persist and look terrible. An oil spray (I recommend, not endorse, "Volck") will smother the crawler stage but once they are established on the plant, only a systemic or hand picking will control them. 'Going forward' as they say, inspect your plants on a weekly basis and try to catch the FIRST insect. You may not succeed in doing that but you will not have a serious outbreak. I would not worry too much about these insects infesting other places like walls and glass surfaces. Routine housekeeping practices will take care of that; but do keep a sharp look out for honeydew on surfaces like plant containers and tabletops.
You have a most interesting challenge and in the end you will be able to teach us all a few things.