Plasma turbulence on a uniform density gradient with unfavorable magnetic curvature is investigated extensively in the Helimak device. The turbulence is strong with density and electrostatic potential fluctuation levels in excess of 40%. Measurements of the dispersion relation, k_z, and k_|| identify the fluctuations with drift-waves, which propagate in the poloidal direction at the diamagnetic drift velocity and have a small, but finite parallel wavenumber. A non-zero phase shift between the density and potential fluctuations gives rise to turbulent cross-field particle transport, which is measured using spectral techniques. In addition, the electrostatic drift-wave fluctuations have a small magnetic component that is driven by the turbulent parallel current j˜ _||. An examination of nonlinear processes associated with the plasma turbulence uncovers high levels of intermittency near the plasma edge and long-time persistence of the density fluctuations on the order of the parallel confinement time. An analysis of the bispectrum confirms the existence local and nonlocal three-wave interactions between unstable drift-waves although the turbulent saturation of the density fluctuation spectrum is likely due nonlinear processes acting in the time domain.