Hey John,
I figured I would chime in as I'm probably the closest dealer to you with one of these actually in stock. We have both the Race and Superrace available for test rides here in Brooklyn. Regaring your questions, the range is dependent on many different factors including speed, assist level, riding conditions and rider weight. I often ride a Superrace personally and I've ridden 20 miles where I only lost two bars of battery where I've also ridden approximately 5 miles using similar battery. For most all you really need is Eco and occasionally bump it up from there. If you ride like this at a conservative speed you will see well over 35 miles. I believe Bosch has a chart on their website giving the range of their speed motor, but I'm typing from my phone right now otherwise I would post it.
You can definitely ride in wet conditions, as all of the electric components are sealed. The motor doesn't really require maintenance as it is a sealed unit. There isn't a traditional water bottle holder so we always find creative ways of mounting. On this bike I might look to something behind the saddle.
The front chainring is one of the larger sizes so I don't believe you'll need to change that. Keep in mind it rotates 2.5 times for every pedal revolution. You may hear of some people swapping them, but it's actually against the Bosch warranty since it could have negative effects on the performance of the bike by throwing the sensors off if the ratios are not maintained.
Feel free to reach out if I can assist further or if you want to come by to test it out.
Best,
Chris