yes
No, that is not a good idea because you want them to enjoy being misted for showers though some of them prefer shallow bowls to take a bath in.
Koalas do not take showers.
Yes
This is an excellent website just on parakeets : http://parakeet.yolasite.com/ It talks about how to care, breed, and train your parakeets.
The parakeets will lay their eggs in a nest that they build themselves. The parakeets will sit on the eggs until all have hatched. The eggs should hatch after 18 days.
People take showers to wash away dirt, sweat, oil, and body odor.
It is possible to take cold showers during the winter, though it may be uncomfortable.
Take them to the vet. Feel better!
yes
no
No 
taking a shower is important or else you will smell. it is unhealthy to not take showers. so yeah, i do take showers. shower everyday 365days a year sometimes more in summertime takes 2 showers a day during the hot season