Investors & landlords

Well I was wondering about my particular situation.  I may have active income... I am only in the dark about the    " at least half of your taxable income"  thing as  I manage my own and had to quit a job in order to repair and manage these inherited rentals - so yeah this is my only "job" for now - possibly forever. I am married filing jointly.  Does my rental income have to match half of his income?   Is that rents received before expenses?   If so, can the total amount of the roof be expensed for that year?