Reading -- totally agree.
Cold weather sailing -- can be fun.
With cold water, protective gear is a must. Either a dry suit, or a extra heavy wet suit for cold water.
Propulsion -- the DS, in calm water, is still sluggish to move. With oars, you can keep it up for a while, with paddles, 200-300' is about the max distance you want to try it for. The higher range is for enthusiastic crew that has something to prove. Mine are about 5-6' long and work well for docking.
Next step up is a trolling motor (40lbs thrust). That works well for calm water in distances of up to 1-2 miles. Fine to navigate short and narrow channels to/from the dock, under bridges, and across smaller calm spots. On a big lake, you are likely going to be out of range to return home on a single battery. (I always bring two). (Many threads on that here, go look them up)
Next step up is the Torqeedo. Fancy battery technology and motor/propeller optimized to act more like an outboard. Expensive, but, for the DS, should be rather functional as an auxiliary.
Or get about 2.5 - 3.5hp outboard. Propane or gasoline. Propane gives you about as much range per small canister as a 12V battery gives you on a trolling motor, but its easier to bring multiple
Goes a bit faster, too. But noisy - very.
On towing -- boat and trailer are a bit over 1000 lbs. Should be fine with most cars. Those not rated may have weaker transmissions and/or brakes. Trailers that size are usually not equipped with their own brakes. There's a thread on towing vehicles here somewhere. But you can probably find discussions on this topic for other sports.
Laptop battery running out, so this is a bit terse for a reply, even with so many questions. Hope it gives you a start.