You're correct. Best would be to turn them off when not in use. One does go off at night. The other gets put on the dimmest setting at night as it's used as a night-light - the only fixture on at night to allow safe passage.
The rest of the fixtures go on and off as needed.

CFLs definitely vary in life with use. I've seen charts showing as little as a few thousand hours if they're turned on for only 5 minutes at a time and up to 20k hours when left on. Starting surges play a profound role in the life of fluorescents.

The quality of the bulb is the key factor. If you buy crap bulbs, they won't last, and unfortunately there are too many manufacturers piling in to make a quick buck and it is giving the field a black-eye.
I've installed a half dozen Cree LR6 "bulbs" for recessed lights. One has been running two years, the others about a year. No failures. Excellent quality light.
While this is about LEDs, I'll comment on CFLs as well because there are a lot of people with similar poor lifespans with those. Again, crap bulbs = short life. I've got a dozen outdoor lights that get used in all temperatures. One failed, the rest have worked without flaw for three years.
Indoors, I've got two living room, 3-way fluorescent bulbs that burn 24/7/365 (yes, this wastes energy but I can't convince the wife to turn them off). Three years and 26,000 hours later and not a failure. I have a bulb above my shower in a recessed light fixture, considered a "worst case" for CFLs - never had to replace since installation 4 years ago.

The fundamental technology is excellent. Many manufacturers suck.

That's excellent.
From a thermodynamics and energy efficiency perspective, we're going to see much more use of waste heat and natural cooling. Right now, buildings systems are not integrated. You have lights, generators, computers, and scads of other heat producing equipment that needs to be cooled by tons of air conditioning capacity. Due to the large cost savings in commercial settings, you can afford to build custom dampering systems as described - bring room air that you want cooled through the datacenter, flush it out, then use this air to heat the space as needed. Once the rooms are up to temperature, introduce fresh air to the data center machines and flush the warmed air back outside (I foresee global warming snark...)

Another option is to use water cooling with a geothermal cooling system. You don't need the heat pump portion, just circulate the water to bleed off the heat then run that into the ground as a big heat sink. Waste heat can first be transferred as needed for operational needs, taking further advantage of the energy.

Finally, another option is to utilize the new heat to electricity systems. They're terribly inefficient in applications at these temperatures, but they could provide a first stage of energy recapture.

As for those worried about humidity - relative humidity relates to temperature. If you take 80% humidity air at 75F and blow it over a hot CPU, the relative humidity will be low. There's no concern about condensation unless the CPUS are running colder than ambient.