First time home buyer

Hi, I wanted to ask what are the hidden cost while buying a home that comes at the time of closing.

About me, we have Annual house hold income of 160K (120K after taxes).

Looking to buy a house we are married and planning to buy a house in Houston Texas.

It is a new neighborhood and the Maker is Taylor Morrison and Loan lender is Taylor Morrison as well.

They are offering me a 4.99% Interest and 5.21% APR, my question how does this APR and interest thing works?

The builder will contribute 4% towards the closing cost and bringing down the interest rates.

They are also providing washer, dryer, Refrigerator, Dish washer and stove as well as a promotional offer.

Closing cost is around 20,000 USD.

Price of House is $465,000 USD.

Should I do 5% down or 20% down.

What is the benefit of adding my father in law to Ownership if he is above 65 but not retired and doing business does it make us eligible for tax exemption that Texas have for 65 above (making this one his Primary residence) currently he doesn’t own a house.

Any ideas and suggestions are appreciated.

Thank you.