The reason not to use automotive batteries is because of the surface area of the electrodes. They are meant to be constantly held at full charge and to supply cranking amps only. Marine/general use batteries are more useful for RE uses, better yet deep discharge rated batteries. They sacrifices overall total amperage (surface area) for anode/cathode durability. For lead acids the voltages and currents you can expect are well provided on the Internet already.
Aside from cranking amps, general use, and deep discharge applications and endless variety of tweaked chemistry's, plate geometries and what not will provide you with more information than you can deal with. Generally speaking since lead acid cells are already batteries in their own right you need complex cell management for higher voltages, and higher voltages are the best way to increase overall system efficiency. Bigger cell sizes are good for general management, but there is a law of diminishing returns. Take a few notes from industrial fork lift batteries. They need incredible amperage ratings, a huge number of cycles and large overall system capacity. System amperage, cycle ratings, and overall capacity will force you to chose one particular section to concentrate on, or go to a more general purpose or hybrid sollution.