What ethnic group is more likely to suffer through depression and then suicide? This is for a project for school. I have a lot more questions too.

Caucasians. Caucasians have higher rates for major depression. There are other factors involved for suicide risk such as gender (male), age (older than 85), and marital status (single, widowed or divorced).
Suicide. Suicide can occur in any ethic group - other risk factors are probably more important predictors than race alone - especially in todays homogeneous society. For instance, young males used to be a higher risk for death from suicide attempts than females, who made more but less lethal attempts. Now we know that bullying or any relentless stigmatization is very dangerous for young people in general. Symptoms are difficult to separate from a young person's reaction to harassment. The same can be said for older men living alone who drink alcohol - the most vulnerable group. Regardless of race or other factors, the most worrisome danger signs are a change in interest level, persistent problems sleeping or eating, a lack of response to happy occasions that goes beyond personal style, and any indication that the person feels trapped or is talking about an big or final solution to a problem. Even a sudden appearance of relief after a period of extreme anguish can signal that a "final" decision has been reached. Do not rely on advice from anyone who has not seen the person directly - including web sites like this one.