Not likely. This question has been studied rather carefully. To my knowledge, there is no association or increased risk of bearing down during delivery in a woman with myopia and consequential retinal detachment; neither the full thickness type (rhegmatogenous) or serous type. The woman should be examined carefully by an ophthalmologist before delivery, particularly with htn, preeclampisa or other problems.
Unlikely. Unless you have extreme risk factors to begin with such as inherited retinal detachment tendency or previous retinal issues, the most likely adverse event in the eye from the strain of labor is hemorrhage on the outside of the eye or in the retina. But these are uncommon, and I have not heard of anyone getting a detachment from labor.
Unlikely. Pushing during delivery can cause other problems in the retina, such as bleeding, but a retinal detachment is unlikely.