Homeland Security Improvement Act This bill establishes various bodies and policies related to border security operations. It also limits when the Department of Homeland Security (DHS) may separate a child from a parent or legal guardian. The bill establishes the independent DHS Border Oversight Commission. The commission's duties shall include recommending policies to protect civil rights and improve the safety of U.S. Customs and Border Protection (CBP) and U.S. Immigration and Customs Enforcement (ICE) officers. The bill establishes the Office of the Ombudsman for Border and Immigration Related Concerns. The office shall independently receive and resolve complaints and requests for assistance regarding border security and immigration activities. The office shall have the power to provide redress, including immigration relief and monetary damages. The bill establishes the Border Community Liaison Office. The office's duties include consulting with communities in sectors on the northern and southern borders when developing policies and programs. DHS must ensure CBP officers receive continual education and training each year on topics including interaction with vulnerable populations and professional conduct standards. The bill imposes data collection requirements on law enforcement officials conducting border and immigration-related stops and searches. A child may not be removed from a parent or legal guardian at or near a port of entry or within 100 miles of the border except in certain instances, such as when a court determines that removal of the child is in the child's best interests. The bill requires various reports, including a Government Accountability Office report on the use of force by CBP and ICE.