Does e.Coli infections affect children worse then adults?

Depends. Really depends on the strain of e. Coli. Some are very virulent and cuase significant organ damage, no matter what the age.
Not necessarily. E. Coli is one of the most common organisms in the gastrointestinal tract (colon, bowel). When it goes to another location, infection can develop. Children tend to have more immature immune systems than adults, so they may be more susceptible to an infection. However, antibiotic treatment can be effective used.