Will I be able to shoot 1-2 hours timelapse in -10 / -5 degrees Celsius? What should I worry about, lens, camera, battery (obviously), memory card?
Can I do anything if I don't have a specialised lens warmer?
Most cameras can function at that temperature, but battery life is much reduced. You can buy an external battery-grip for some cameras, e.g. this Nikon battery for the D750 for ~US$340. I made a larger external battery pack for a Panasonic FZ1000 from a DC adapter and a few 18650 cells, below for ~US$50.
Depends on the camera.
From personal experience, my DSLR (Canon T6) didn't like much when I tried to use it, unprotected, at -17c. I felt the shutter getting slower, not sure if it actually was.
My GoPro session 5, on the other hand, took it like a champ. (Video here: https://youtu.be/D14KsdosU7E ). Most gopros have timelapse mode, and I know that the session can do about 1h30mins of timelapse with the internal battery. I hook it up to power or to an external USB battery if I want more than that.
My point being: That's GoPro territory. That damn thing works even inside liquid nitrogen. (https://www.youtube.com/watch?v=JZFpJ6DnWrg - that smaller one, without the screen is the session)