Those are legitimate questions. Let me give you what information I have.
The mercury in a fluorescent bulb is excited by applied electrical current to produce UV radiation, which in turn causes the coating of the bulb to "fluoresce" -- to give off the visible light we see from the bulb. Roughly, the amount of mercury in the bulb is proportional to the amount of light expected from the bulb, which is in turn proportional to its wattage. So one would expect a standard 4-foot long 40-watt tube fluorescent to contain perhaps four times as much mercury as a 9-watt CFL (the "40W-incandescent equiv."). The CFL considered equivalent to a 100W incandescent is about 25W, so about half the mercury of the 4-foot 40-watt fluorescent tube.
That approximation is "with all other things being equal". They're not -- CFLs are in general designed to use less mercury than the older styles of bulbs, for the same output, in that they only use enough mercury to last the expected lifetime of the bulb, with no excess. Older bulbs were typically manufactured with extra mercury. How much extra? I don't know offhand, probably could find out.
So it is NOT correct to merely count bulbs. A CFL contains much less mercury than a 4-foot tube. Unfortunately I do not have exact figures, because they vary with style of bulb, manufacturer, etc. But given the environmental regulations now in effect, I have to believe those numbers are available from the manufacturers as a matter of public interest.
> Admittedly, I have a fierce prejudice against the CFL.
I don't share your bias, largely because I have used CFLs exclusively for 20 years in my off-grid, extremely low-power-budget PV-powered house. I used the early OSRAM bulbs (awful) and Philips bulbs (also awful) and a variety of others (varied but mostly awful). But I have seen them improve over those 20 years to the point where I consider them pretty damn good, the last 5 years or so.
That said, I still prefer the warm glow of an incandescent for certain activities, and I am anything but a purist about CFLs. And I especially dislike the government forcing this issue, and resent it even though I'm already using the things.
Which is least awful these days?
I am still interested in knowing the rough figure of how many incandescent bulbs are in use in the US. Also, I have started to collect other data (found below).
I found this data (not dated---I presume the Q&A was posted in 2006, but have no way to be certain):
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How many light bulbs are there in the world?
Answer: According to fastcompany.com: "Last year, U.S. consumers spent about $1 billion to buy about 2 billion lightbulbs--5.5 million every day."
According to wsj.com: "The U.S., which has four billion electric lights using [incandescent] bulbs, represents about a third of the world market."
Below are two articles bearing same title with different contents:
How Many Lightbulbs Does it Take to Change the World? One. And You're Looking At It. [Sept 2006]
How Many Lightbulbs Does it Take to Change the World? One. And You're Looking At It. [Dec 2007]
Also of possible interest:
South Carolina Taking Light Bulb Ban into Its Own Hands [May 2011]
QUESTION: Have you experimented with LED bulbs? Have an opinion?