Painting a house

Preprime your raw spots and speckled areas. Otherwise you'll get bleed through and flashing. I was a painter for 15 years professionally and have painted on the side for the last 10. Generally spraying gets you about 150/200 sqft per gallon whereas brush and roll is twice that. So you should be close with 5 gallons as long as you don't need to recoat it much.