On the subject of torches, I use a head mounted light (such as can be bought from camping shops) with a red filter - makes instrument scans much easier if you're flying an a/c with very few of the inst panel bulbs working. It also makes approaches a bit easier, when you're trying to set flap, throttle, attitude, move carb heat, trim the aircraft - juggling a torch ain't easy!! I also carry a Maglite with red filter, also one with white light (for checking things like oil levels, which is never too successful with red light!).
Night vision takes around 20 mins to establish and can be destroyed instantly if the a/c in front has his strobes on when taxying! Red light tends not to affect night vision, so if you do have to use white light, use your index / 2nd finger over it and just allow them to separate slightly so you get just a little dim white light (I've done a fair amount of night exercises in the RAF and had to do night navigation, so I've learnt the hard way!). To avoid mistakes in the air, if you're using identical torches for red / white light, then put some insulating tape around the base of one so you can feel which is the red and which is the white!).