The map is huge and confusing. The only thing I remember was the Q diamond,
and never understood what it did, compared to the Normal Q line.

It's not really any more confusing than the Southern Region local
trains in London. It's just a completely different style of system
from the Underground.

As for the late Q-diamond, as far as you were probably concerned (I
assume you only used it between 57/7 and Prospect Pk) it was no
different to a regular Q train. South of Prospect Pk, the circle ran
local and the diamond express. Since February 22nd (when the North
Side of the Manhattan Bridge reopened), the circle Q remained as it
was and the 6th Av B train became the Brighton Express. This caused
quite a stir as the historical pattern was Q Brighton Express, D
Brighton Local, and B West End.

The one thing that annoyed me. You swipe the tickets in a turnstile like
they do with Credit cards in a shop, but my card refused to swipe and I
spoke to the unhelpful man in the glass box and he muffled something to me
in another language, and he opened the side gate, which I went through, and
held open for about 3 others. Their revenue protection is awful. Anyway, I
missed a train and sat on a horrible platform with 10 buskers and watched
the dogs/rats run along the track and loud trains whizz through the middle.
Think of the Central line at bank and times the noise level by 5.

There's certainly a knack to swiping your Metrocard.