So all the engines are all "plumbed" together?

Yes.

As long as one of the 8 is running,
you can send "starting air" to the others (within the limits you mentioned.)?

Yes.

Starting is all with bleed air, no electric motors?

The starters ("spark") are DC, but initial engine rotation is provided by bleed
air.

Given all this complexity, why was an APU not fitted?

Are there any jets built before 1962 that have APUs? Did the Comet have an APU?
If the answer is yes to either of those, my only guess would be, to save
weight, they did without the APU. Hell, they took the G model's and H model's
ailerons off to save weight.


BUFDRVR

"Stay on the bomb run boys, I'm gonna get those bomb doors open if it harelips
everyone on Bear Creek"