Loan Questions for a Seller Financed Loan

I'm new to this so please bear with me. If I was interested in purchasing a seller financed home with the total price of say $700,000, could the loan be structured to pay off say $150,000 to the seller over a 4-year period with the remaining due after that period? For example, I would need a new loan from a bank for the remaining $550,000 after the 4 years or would refinance the house for the $550,000, correct? This is assuming the house is paid off prior. 

The idea here is to pay off the principal of the $700,000 over the four period then when I get a loan for the remainder $550,000 it would be more affordable. Thanks in advance!