I am not sure about item #1. I suspect unless you expect freezing weather, there is little to worry about, and realistically, it is not much of a concern.
Lock mechanisms end up getting wet regularly without harm.
Some WD-40 sprayed in the lock may help displace water and will lubricate the lock.
The second question indicates a problem with the wiper motor or wiring. The small movement you see is actually the 'park routine' and is a separate operation of the wiper motor from the main wiping action.
Therefore, when you see only the small amount of movement, the park routine is receiving power, but the main wiper routine is not, either through lack of electrical power or a non functional relay. IMO change the wiper motor. It would be a severe hazard if your wiper motor stops working in traffic just as it starts to rain.
BTW your 2.7 liter engine is notorious for engine sludging problems. Be sure to use fully synthetic oil in your oil changes. Ordinary oils become overheated by the normal operation of the engine (due to a design flaw), forming sludge and clog the cam chain adjusters, eventually allowing the chain to skip and pushing the valves into the pistons; an expensive repair.
Synthetic oils do not create such sludge under such conditions.
Otherwise, its a fine car. My dad has the same model and year as yours.