Ignore #5 or think of it a supplemental revenue stream. Revenue from banner ads seems to be on the decline. Ab blockers and what not. My gut says that it's not a good way to fund your job board for the long haul.
I should have been clear, I did not mean the annoying ads that bring in cents for clicks. I meant sponsored banners on the side that costs $100-$200/a month for the employer to put up their brand.