The effect of various couplings on the switching field and coercivity in NiO-Co-Cu-based giant magnetoresistance (GMR) bottom spin valves is investigated. Bottom spin valves as well as different layer permutations that make up a bottom spin valve, viz., Co single films, Co/Cu/Co trilayers, and Co/NiO bilayers (deposited under similar growth conditions), were investigated for their magnetic, crystal, and interfacial structure. As-deposited bottom spin valves exhibit a large GMR of \ensuremath{\approx}16.5%, and a small net ferromagnetic coupling (+0.36 mT) between the ``free'' Co layer and the NiO-pinned Co layer. The high resolution transmission electron microscopy (HRTEM) and in situ scanning tunneling microscopy (STM) studies on spin valves and trilayers show that the average grain size in these films is \ensuremath{\approx}20 nm and average roughness \ensuremath{\approx} 0.3 nm. Using these values, the observed ferromagnetic coupling in spin valves could largely be accounted for by N\'eel's so-called ``orange-peel'' coupling. Results also show that the ``free'' Co layer exhibits an enhanced coercivity ${(H}_{c}^{\mathrm{F}\mathrm{r}\mathrm{e}\mathrm{e}\ensuremath{-}\mathrm{C}\mathrm{o}}=6.7\mathrm{mT})$ with respect to Co single films of comparable thickness ${(H}_{c}^{\mathrm{Co}}=2.7\mathrm{mT}).$ The TEM studies did not reveal the presence of any pin-holes, and ``orange-peel'' or oscillatory exchange coupling mechanisms cannot adequately account for this observed coercivity enhancement in the ``free'' Co layer of spin valves. The present study shows that the often observed and undesirable coercivity enhancement in the ``free'' Co layer results from magnetostatic coupling between domain walls in the ``free'' Co layer and high coercivity NiO-pinned Co layer ${(H}_{c}^{\mathrm{P}\mathrm{i}\mathrm{n}\mathrm{n}\mathrm{e}\mathrm{d}\ensuremath{-}\mathrm{C}\mathrm{o}}\ensuremath{\approx}45\mathrm{mT});$ without NiO, the coercivity of Co layers in the corresponding Co/Cu/Co trilayer remains largely unchanged ${(H}_{c}^{\mathrm{C}\mathrm{o}/\mathrm{C}\mathrm{u}/\mathrm{C}\mathrm{o}}=3.0\mathrm{mT})$ with respect to Co single films. Evidence of magnetostatically coupled domain walls was confirmed by direct observation of magnetization reversal, which revealed that domain walls in the ``free'' Co layer are magnetostatically locked-in with stray fields due to domain walls or magnetization ripples in the high coercivity NiO-pinned Co layer of the spin valves. The observed escape fields (defined as fields in excess of intrinsic coercivity of Co single film that are required to overcome magnetostatic coupling between domain walls) are in agreement with theoretically calculated values of escape fields.