The purpose of having a cockatiel cage is because they need plenty of room to move around and so you can put objects in the cage so they can climb. The birds love to have plenty of things to do in their cages.
The spaces between the bars are probably too wide for a cockatiel. It would be able to get through them.
yes
No it's fine to feed cockatiels in their cage. I feed mine in their cage as they will not eat out of my hand. Just make sure you clean their cage thoroughly every day, including perches, dishes, toys etc. Also make sure your birds have vegetables and fruit to eat aswell as seeds or pellets to keep them healthy.
It really all depends on the birds personalities. Parakeets of good nature, and Cockatiels of a similar nature are good together. If there is any aggression between the two before you put them in the cage together, then keep them separated. The parakeet could get severely injured.
A budgie and a cockatiel are all right together in an aviary. It would be better for them to not be together in a small, indoor cage.
If there is no male in the cage, they will lay eggs, but they will not be fertile.
remove her from the cage then remove egg
Small parrots don't do well with big ones, the African grey will become dominant, and it will act aggressively with the cockatiel. a cage is not a good idea no matter how big it is, only an aviary will be good enough to house them.
It depends on the cage. The color, material, size, sturdiness, ect. To get a fair sized, study, long lasting cage, it is usually between $150-200.
yes
Your cockatiel is flinging all the other seeds out of the way as it tried to find its favourites in the seed dish. Make sure you have a decent cage protector for the lower half of the cage (available from any pet shop) and this will minimise the problem (but it will not eliminate it completely).
if a cockatial is at the bottom of its cage and on its side with its eyes closed then its dead but if its up on a stick or on the side of the cage with its eyes clsed then its just sleeping