Can multiple bank accounts be used for direct debit payment of personal income taxes due or only 1 bank account for direct debit payment?

You cannot do a split payment in TurboTax, but you can do a split payment through one of the IRS payment sites.  

• What you will need to do in the program is select "I will mail a check" as your form of payment, then File your return.
• Then visit http://www.irs.gov/Payments and select "Pay by Card".  
• From there you will be given the option to choose one of the IRS approved payment sites.