In these sunken-into-the-ceiling "cans" into which
you screw-in light-bulbs (not much grip-room around
the sides), a (burnt-out) (indoor flood) can be darn near
*impossible* to unscrew, at least without breaking the bulb.
CY: I hear yah.

QUESTION 1: hints and tricks on (safely) unscrewing the
things -- including the small 2or3-inch-across ones too.
CY: Wear rubber glove. They are more grippy.

And, what about the rubber press-on (causing vacuum seal)
kits like they sell at HD? Do they actually work?
CY: Dunno.

QUESTION 2: might it be a question of the *quality* of
the socket (material)? (Ours came from HD!)
CY: Like dentists who push high fluoride tooth paste on their
victi////patients?

Do these things come in different quality, different
materials? (Aluminum vs aluminum-coated-with-something vs
maybe copper?)
CY: I'm sure they do.

QUESTION3: short of that (could be expensive?, difficult
to do?), is there some kind of a (conducting, of course)
lubricant than can sprayed or rubbed onto either the
socket inner-surface or the bulb screw?
CY: You don't want a conducting lubricant. It will tend to short out
the fixture. I'd try old fashioned axle grease. High temp lith maybe.