I am putting it up for the winter. Do I keep the battery (about 60% charged now) inside for the winter? Anything else?

It's great to hear about your plans for winter storage of your ebike. The advice you've received in this thread is quite comprehensive and aligns well with best practices. Bringing your battery inside is definitely recommended, especially in extreme cold temperatures like -15 F. Storing the battery at a charge level of around 30% to 60% is ideal to maintain its health and longevity. Full charges or complete discharges can put unnecessary strain on the battery.

Additionally, as others have mentioned, avoid charging the battery in freezing conditions. Room temperature is the best environment for both storage and charging. Regarding your hydraulic disc brakes, they should be fine if they've been regularly maintained.

If you have any specific concerns about your ebike model, especially regarding battery care during winter, feel free to reach out. We’re here to help ensure your ebike and its components stay in great shape throughout the colder months.
I would read the owner's manual for long term storage and restrictions in below freezing temps.

My Himiway 48v 20AH Samsung/LG Li-ion suggests not to store in near/below freezing temps, NEVER EVER deplete the battery, top off power on every ride, and store fully charged and top off to 100% once a month. Don't know the differences in the Himiway battery construction/electronics; but, they recommend to always keep the battery pack at 100% when not in use to improve longevity.

(from the manual)
Battery Maintenance (48V 20AH Samsung/LG Lithium-ion battery)
Don't fully drain your battery. Turn off the power when the battery charge is low.
Fully charge the battery after each use, no matter how much power is used. This will prolong the battery life. If the battery is not used for a long time,
store the battery with a full charge and charge it once a month.
The Himiway Bike can be safely ridden in light rain. However, riding through very heavy downpours or through flooded streets is not recommended, as the
crank and/or motor can get wet, which may cause problems.
Keep the battery away from open flame or a high-temperature heat source. Do not expose the battery to direct sunlight or recharge immediately after
use in high-temperature weather.