First thing DONT google!!! It will scare you stupid.
Second AML tends to be more difficult to treat than ALL (Acute lymphoblastic leukaemia) but this is not always the case. Treatment tends to be shorter and sharper than for ALL (ie 6 months intensive chemo rather than 2-3 years predominantly outpatient based as in ALL). AML M7 can have a poorer outlook but it very much depends on other factors such as the cytogenetics (chromosome issues). AML M7 is more common in children with Downs but for some reason their prognosis is slightly better.
Bone Marrow Transplant could be an option. The mixed race thing can make finding a donor challenging but not impossible. The option of BMT will depend on cytogenetics, response to initial chemo courses, donor options etc etc.
Hope that helps-you sound like a lovely friend and I am sure the family will need you lots over the next few months. You have to remember that each child is unique and their response to the disease is also unique so talking in terms of survival rates /prognosis is not always that helpful tbh.
Hope that helps