Depends. E coli are normal part of the colonic bacterial flora and this relation is mutually beneficial. Some strains of e. Coli are pathogenic and are bad.
No. E. Coli is a very common (and normal) bacteria found in the human intestinal system. It is only certain strains that can be deadly if infected.
No. Every human and most animals have E.coli as an innocent hitchhiker germ in their intestines. The germ is a family of many strains, & some strains are more worrisome than others, since they can create toxins, cause bad diarrhea or even kidney shutdown.