I'm sorry to hear about your little sister. You may well have found an answer to these questions by now, but I have an answer below for the sake of others who may have similar questions. I assume you are asking about Acute Lymphoblastic Leukaemia or "ALL".
The American National Cancer Institute has very comprehensive and well presented material online. This is for health professionals [ https://www.cancer.gov/types/leukemia/hp/child-all-treatment-pdq ] and also information which is for patients / parents [ https://www.cancer.gov/types/leukemia/patient/child-all-treatment-pdq ].
Significant advances in ALL treatment and prognosis have been made in recent years:
" For ALL, the 5-year survival rate has increased over the same time from 60% to approximately 90% for children younger than 15 years and from 28% to more than 75% for adolescents aged 15 to 19 years."
Ref: Howlader N, Noone AM, Krapcho M: SEER Cancer Statistics Review (CSR) 1975-2013. Bethesda, Md: National Cancer Institute, 2015.
This applies to the US & UK population (intensive chemotherapy with excellent supportive care, which is costly), but as I'm not sure where you are based I cannot answer about the prognosis in your area.
I'm afraid I cannot answer your third question about supplying chemotherapy.