The B1 visa is a business visa, but not for employment. It is for attending business meetings, giving speeches, attending a short training class, etc. The B2 tourist visa is for tourism (including visiting friends & family), plus coming to the US specifically for medical treatment. Many people apply for the combined B1/2, even if they don't anticipate business travel, because the cost and paperwork are the same. If you do not envision any business travel to the US, you may want to only apply for the B1. Most Haitians receive a B1, B2, or B1/2 that is valid for multiple entry over 5 years.
The two main tings you have to demonstrate is that you have sufficient funds for your trip and that you have such strong ties to Haiti that you will definitely return. The strong ties are more important than the money.
Strong ties include things like a job, ownership of a business, being accepted into university, owning property, having a lease on a flat, having bank accounts or other investments. Then there are "social ties." A spouse and children, or at least lots of friends & family in Haiti, Belonging to a church, a sports group, or a club that is very important to you. Needing to return to attend a wedding or celebrate Grandmother's 100th birthday. Your elderly parents rely on you for money or other support.
Yes, put down "relative" for your ant & uncle.