1) If you want to expand later, you'll either be replacing all your components, or buying capable enough components up front to handle your eventual needs once more batteries and panels are added; I would be inclined to the latter.
Eric Hammond wrote:I can highly recommend the simple pump well pump with the linear bearing link drive solar motor. Works awesome. Mines a 24 volt. Its a slow pump like about 1 gallon a minute or less. You fill a large reservoir tank with a float switch and then plumb a booster pump inline to a regular pressure tank. Then viola, running pressurized water.