What are the problems that vertebrates required to solve to adapt to the terrestrial environment as they came from the aquatic habitat? How evolution does solve those problems?

The main problems vertebrates coming from water needed to solve to adapt to the terrestrial environment were the following: the difficulty to avoid dehydration; the problem of elimination of wastes in a medium where water is fewer available; the problem of protection against nocent solar radiation; the problem of gamete locomotion in the environment for fecundation; the problem of gas exchange, earlier completed by direct contact of water with gills; the problem of body support, as it was water that played this role in fishes.