Who was the lead singer and writer , composer/s of "Pink Floyd"? and where from exactly?

when they made their songs,,most of them and how popular and how came
to be popular? were they instant hits on the radio in britain? how
compared to the USA and WHICH SONGS WERE MOST POPULAR IN FIRST? AND
HOW DEVELOPED?

also, have they changed writers, composers, singers, etc? how they did
this, when and why?

as i think "The Wall" was very good..and "Division Bell" was very
interesting..but others are just not as good,,i think,,,how true or
not and why?

ALSO, DID THEY MAYBE HAVE THEIR CREATIVITY FLUCTUATING DUE TO
DEADLINES, CORPORATE PRESSURE..AND DRUGS UPS AND DOWNS OR JUST DOWNS?

please explain how this is same for other artistic groups...they
always seem to have the good stuff in the beginning and then down
hill..except for a few...why this is?

any examples too appreciated.

thanks for your answers!