When is my bank account finally debited if I use Apple Pay ?

Apple Pay is just a method of delivering your payment choice electronically.

1. For example, does use of my iPhone with Apple Pay result in a transaction appearing in my credit card account, just as if I had used the card, and hence I receive a monthly account statement from my credit card provider, but nothing from Apple? If this is so, will the transaction details captured by using my phone be the same as those I see in my statement when using my card?

1. Yeah, I know I'm too old to understand this, but so far, among the many on-line descriptions of Apple Pay, I have found no explanation of how an Apple Pay transaction gets completed with funds leaving my bank account.

For example, does use of my iPhone with Apple Pay result in a transaction appearing in my credit card account, just as if I had used the card, and hence I receive a monthly account statement from my credit card provider, but nothing from Apple? If this is so, will the transaction details captured by using my phone be the same as those I see in my statement when using my card?

If you elect to use a credit card using Apple Pay, it is just as if you present a physical credit card in the store. Your charge should reflect the merchant (although I've seen one case where it simply says Apple Pay).

. Or do I receive a monthly 'statement' from Apple - meaning that Apple is providing credit services? And how is that monthly statement paid-off and reconciled against receipts, (which I always get from contactless card transactions}? Does Apple provide me with this (monthly ?) account statement in the form of a debit to my credit card account - as they currently do for my monthly subscription for iCloud storage ?

Nope. No statement from Apple, unless you have an Apple Card then your statement is posted directly in the wallet.

. Why is none of this fully explained in any document about setting up/using Apple Pay? What advantage or disadvantage is there to Apple or to me, by obscuring this important information?

It seems to be unnecessary as all you're doing is presenting a digital version of your card.