Chametz (Exodus ch.12) is leavening or leavened goods such as bread, cakes, and many other products. Torah-observant Jews do not eat them in Passover.
Some kosher companies make cereals that are Kosher for Passover.
Chametz can be eaten in Jerusalem until the morning before Passover and cannot be eaten again until the end of the Passover season. The exact time until when chametz can be eaten is publicized locally in Jewish communities. Some religious Jews burn or destroy any chametz they have in preparation for Passover.
No, bulgar is chametz.
Perogie dough is made with raw flour and therefore is chametz. They cannot be eaten during Passover.
Bran is derived from grains and therefore chametz.
Baklava, which is made with phyllo dough, is chametz.
Yes. Dog food is probably chametz on Passover and may not be owned by a Jew on Passover. Most dogs will happily eat Matzo and meat/chicken on Passover.
There are brands of kosher for Passover baking powder but they have to be marked specifically for Passover.
No, tortillas and other flat breads are chametz.
Yes, and most cat foods are NOT kosher.
Real granola, which contains oats and wheat, is chametz and cannot be eaten during Passover.
If something has no grain in it, and did not come into contact with something that had grain in it, or even if pots are hot enough, and chametz touches the pot, and the non chametz touches the pot, it might be chametz. The laws are complicated, and this is not the right place for them. Also, many have a custom not to eat legumes on Passover because their flours' are simuler to grain flour, or possibly because kernals of grain would get mixed into them, and still do sometimes.