Use http://guideguide.me/ with Adobe Photoshop and analyze your website PSD to determine how many rows you need, as well as how many columns, the column widths, and the gutter widths.
You are not just building one site, but 3 different sites. A desktop site, a pad version, and a mobile version.
Every website needs navigation. Foundation really pushes you towards a dynamic top nav, so make sure you are including the topbar js application (foundation.topbar.js, and make sure top-bar.scss is being compile into your foundation.css file), or the new side-nav(side-nav.scss) or sub-nav(sub-nav.scss)