welcome, piko!
This and
this should get you up and running.
as far as repotting, I'd say it's probably just fine as it is. if you do feel you must repot, make sure you don't use any old soil! the whole reason venus flytraps need to eat bugs is because they live in very nutrient-poor soil. so if you used garden soil, or anything with any sort of fertilizer or nutrients, you'd probably kill it! there are more details on the links above, but basically you want to stick with sphagnum peat moss or a 50/50 mix of that with sand or perlite.
also, VERY important, use ONLY distilled water (available at a drug store or supermarket) or rain water for your vft! any other water could potentially kill your plant because of the minerals it contains.
as far as the temperature drops at night and the humidity, well...I'm no expert...but here are my best guesses:
since the temperature drops are so extreme, you might want to take the plant inside at night. the reason I say that is because the nighttime temperatures are similar to wintertime in their natural habitat...which could mess up their signals to go into dormancy. do, however, keep it outside during the day...the more sun they get the better!
and venus flytraps are actually quite happy if you stick their pot in a water tray. this will keep their soil nice and wet, and also improve the humidity around the plant as the water from the tray evaporates. try about an inch of water (remember, distilled or rain only!)
good luck!