If I signed up for a payment plan, does the money automatically come out of my back account each month?

Depends on how you set up the payment but if you do monthly direct debits then the fees are less ... do NOT set them up thru TT ...in the FILE tab choose to "mail a check" then either send a partial payment then wait for the IRS bill then make another payment ( just like a credit card)  OR  go online at www.IRS.gov/payments . 

Good to know now that I owe even more money. Why can they charge money when I was approved for payment?