All of the information used to complete the information on 1098 should be based on what is in 1098. Whether to enter the origination date or the date you purchased the home. Are these loans all for the same property and you have more than one mortgage on the property or is each loan for a different property.
No, the date the home was purchased for each of these banks should not be the origination date of each bank that was already entered on the 1098.
In response to the second paragraph of your question, Column 1 would be the amount that is in Box 2 of the 1098. Column 2 would be the date you paid the loan off. If the loan is not paid off, then you need to leave it blank. For Column 1, Box D, if this is the loan you took out in 2021, this amount would be blank. This column wants to know the balance of each loan o 1/1/2021. If Column 2, Box D is the new loan, you would enter the date of the last payment.
Because of the number of 1098s, TurboTax is just asking additional questions to clarify/confirm that you are entitled to claim all the interest. The IRS only allows you to claim the interest on two loans (primary residence and secondary home). If any of the loans are home equity or line of credits, you can only take the interest if the funds were used to make improvements, renovations to your home - the phrase is "buy, build or substantially improve.
