yes
Yes, cows have more than one stomach. that is what rumen is more than one stomcah.
You may be confusing "heart" with "stomach." No mammal has more than one heart. Several animals have more than one stomach, or multi-chambered stomachs. These are called ruminants. a Ruminants are mammals in the order Artiodactyla. They predigest their food in the first stomach, regurgitate it, re-chew it (it is called cud now) and re-swallow it.
No. Cows only have one stomach, but that stomach is divided into four chambers or compartments.
Yes, They are mammals
They are an animal that ruminates. It has more than one stomach.
No.
1 and that's a cow
Yes, you can get viral gastroenteritis (in common terms, a "stomach bug" or "stomach flu") more than once.
Many things would be considered to be more malicious than stomach ulcers, one of which would be gastric cancer.
Elephants are not ruminants and therefore do not have four stomachs. Their stomach is very similar to mammals with a simple stomach much like our own.
enough to fill its stomach
Your question doesn't make sense as there is more than one cause.