Yes, frost free, at least at the level of the benches. The pots near the bottom vents will freeze sometimes. The gas heater comes on when the roof gets down to 45F. The exhaust fans come on when the temperature rises above about 55F so it is a fine balancing act to save blasting all that expensive warm air back out!
The smallest round pots are about 5", the 'terracotta' ones are about 6 1/2" and the big round ones about 9". They don't get a drop of water from mid-June to mid-September but I'm sure they never get completely dry. It still amazes me when repotting bulbs to find damp compost at the bottom of a square 4 1/2" pot a couple of months after it was last watered - and that is with our heat. The 3 1/2" pots all dry thoroughly - it is amazing what a difference an extra inch makes.
These pots remain uncovered in summer, but I put 1/3" thick sheets of building insulation styrofoam over the other cyclamen once fully dormant - it really helps prevent desiccation, particularly with the seedlings. Hederifolium always desiccates first - but the tubers look just as tough as graecum and persicum, whereas mirabile looks very suceptible but never desiccates. Coum and the repandum complex are somewhere in the middle.
With us hitting the high 80sF over the next few days, and with undiluted sun for weeks now, I still have 60% shade cloth on the greenhouses. I'll probably roll it up some at the weekend, as the leaves are starting to appear.
I water overhead using a 15" wand - a great tool that makes a fine but powerful curtain of water and is perfect for watering a lot of pots evenly.
Best,
J.