there's not too much to answer, though.

a) performance RWD cars with 2 or less doors, mainly from the 60s and 70s.
If there wasn't a history with racing, no pics with numbers on it or where they slide – then they rarely make the pass.:-)

Even my bulkiest ones were successful in racing, like the Charger 71 or the Superbird.
This is why I have Commodore, Omega or Foxbodies, but no Granada.

1960s for style and history and technical transition, 1970 for the wild experiments of this era.
Older and newer only if something really strikes a chord.

b) never checked, and what for?

c) No "typical years" exist.
I sold 80 at once as a bulk in 2021.
In 2022 just a handful, whenever I noticed someone in a forum searched for something I never cared much for.
In early 2023 I sold perhaps 30 or 40 cars, but since and in this running year none at all.

Depends on time, space, money. The usual.

"Everchanging collection", not really.
The Tyrrells shown above are here for 10 to 15 years.
Since they came out.

I do buy cars since the late 80s, many are still here.