Understanding a balloon payment

[Wesston Faux]

Hi there,

My question is regarding balloon payments.  I saw a deal posted on realtor.com as follows:

Fully rented brick 4-plex. Seller will finance with terms acceptable to seller. Minimum 20% DOWN, Accept SELLER'S EXISTING LOAN TERMS WITH AN ALL INCLUSIVE DEED OF TRUST. INTEREST RATE 3.25% AT TIME OF LISTING with $600 P & I payment with 3 yr Balloon

1) What is an all inclusive deed of trust?  I looked up some definitions...So the seller still has a mortgage...I pay him, he pays the bank, and if I default he takes the property back?  Is that accurate?  What advantage does this give to the seller?

2)When the balloon payments becomes due at the end of 3 years, how is that paid for?  Does the bank then allow me to take out my own mortgage on the property to then pay the seller off?  Thanks in advance for you help.

Ps, asking is 144k, rent is 1775 total, tax ~3k, unsure on utilities, insurance probably ~45/month