On occasion, I run at night. I only run on roads and would be concerned about tripping over a fallen branch or something on a trail at night.
When I do run at night, I am sure to use extra reflective material (most shoes, shorts, and shirts come with it now days). I'd guess you'd want a head lamp at night. I used to use a blinking light clipped onto the back of my shorts. Blinking lights are pretty easy to find around Halloween time. It's great to buy a bunch right after they go on clearance after Halloween. They are made pretty cheaply and don't last very long.
If you are switching to night running because of daytime temps, I'd be surprised that running at 9 - 10pm wouldn't be close to the same temp as 1 - 2am. For me, running at 9pm means that I could still shower and sleep after my run while still getting to bed and up for work at a reasonable time. To run at 2am would kill my already lousy sleep schedule.
FWIW: I hate running on a treadmill. If you've never used one, I'd suggest trying it before spending a significant amount on a treadmill.