Below is how I would answer your questions: (Tell me if I didn't answer any of your questions well enough)
1) GST incurred on credit purchases is treated as if the GST was paid directly to the ATO. Therefore, it would decrease the GST liability (or increase the GST asset), which would be debited from the GST Clearing account.
2) The creditors control ledger describes the overall debits/credits on creditors, while the Creditors Ledger describes transactions with individual creditors, with their respective dates.
(I don't know if I explained that well enough)
3) The Purchases Journal is posted to the creditors ledger using the individual transactions on the date they occur.
The purchases journal does not use a double-entry when recording in the creditors ledger, while the general ledger will have both a debit and a respective credit entry.
4) -6) You already answered them?
7) The debtors control ledger describes the overall debits/credits on debtors, while the debtorss Ledger describes transactions with individual debtors, with their respective dates.
(Copy and paste from q2 - changing creditors to debtors
)
The Sales Journal is posted to the debtors ledger using the individual transactions on the date they occur.
The sales journal does not use a double-entry when recording in the debtors ledger, while the general ledger will have both a debit and a respective credit entry.
(Copy and paste from q3 - changing Sales to Purchases
)
9) The Debtors Schedule not only gives an overall balance, which can be checked with the debtors control ledger for accuracy, but it also lists all the balances of the each debtor in its calculations. These features assist in the control of debtors.
10) You already answered it.
11) The account to be credited in the Cash Payments Journal is always Bank. Thus, as it is always the case, it is not Relevant to mention this in the details column. It is for this reason that the amount to be debited, which varies with different transactions, is stated clearly in the details column.
12) The sum of all the debit columns, which should be equal to the total of the Bank column, is used as the amount to be credited to the Bank, which is cross-referenced to "Cash Payments." Each individual account, which includes the debit items in the payments journal, including each individual sundry item, must also be debited with their respective transactions.
13) The Cash Payments Journal is posted to the creditors (subsidiary) ledger using individual transactions on the day they occur, while the Creditors Control account, contains only the overall debit/credit entries and is only posted at the end of the reporting period.
The Cash Payments Journal is posted to the General Ledger using a double-entry recording system (i.e. a debit + a credit). The creditors ledger only has the debit entry, cross-referenced to bank.
14) The account to be debited in the Cash Receipts Journal is always Bank (asset). Therefore, it is not relevant to state it in the details column. As a result, only the credited account is stated in the details column.
15) The name of each debtor is stated in the details column to allow for posting to the debtors ledger. Without the names of each individual debtor, the user of the journal, could not post to the debtors ledger, because no specific details were given.
16) While the Cost of Sales column has no effect on Bank, it is still necessary to state the amount of the Cost of Sales expense because it is an expense related to the cash receipt of sales. This amount has a direct relation to each individual sale and must also be stated for accurate profit to be recorded. Consequently, it is used in the Cash Receipts Journal.
17) The Cash Receipts Journal is posted to the debtors (subsidiary) ledger using individual transactions on the day they occur, while the Debtors Control account, contains only the overall debit/credit entries and is only posted at the end of the reporting period.
The Cash Receipts Journal is posted to the General Ledger using a double-entry recording system (i.e. a debit + a credit). When posting the Cash Receipts Journal, the debtors ledger only has the debit entry, cross-referenced to bank.
18) When cash is received from debtors, it is always a "receipt from debtors," which decreases the debtors control account (in the form of a credit) and increases Bank, which is debited. Therefore, as the debtors ledger shows the individual debtors account, they must always be cross-referenced to Bank.
19) When a discount is received, the bank column states the "amount that was actually paid" (i.e. the value of the payment - the discount revenue obtained). The creditors column uses the "total value" of the payment, as this was the value of the decrease in the creditors account.
20) When a debtor receives a discount from a firm, the firm's bank column, states only the amount that was actually received (i.e. the value of the receipt - the discount expense incurred). The debtors column uses the "total value" of the receipt, as this was the value of the decrease in the debtors account.
21) The amount posted to the debtors control account is the decrease/increase in debtors balance. However, the debtor may have received a discount from the firm, to which the cash received from debtors would be less than the value shown in the debtors control account.
22) The credit to the debtors control account, refers to both the amount received and the amount of discount expense, which was incurred in the period. As a result, the cross-reference must be for both discount and Bank.
I'm not sure if I answered all the questions to a 100% quality.
Hope I helped.