1. 170 degrees
2. You can buy ( I dont know this words ..it is like wire with lock .that turn into shutter turn on exp and lock. go to night drink. and after 30..50. ..90 min turn lock off, ... - On f 4 and 90 min at 100 ASA on field without street light or city light around exp was +2. More minute need for stars line -and meteors.
100 ASA at f4. There was few street light (and no city light around !) at distance about 300 to 500 meters (yards) and that made tripod shadow. On place in reel life you can see anything except deep night -withot Moon!!!!
good luck and ask if I can help!
I made so much experiment at negative, photo and lab, walk into my gallery, welcome !