请教老师几个问题，我哥哥一家的F4移民B表排期到了，下一步我们要做什么？

Wait for USCIS to send notice to petitioner in US? 

My brother has moved in the past years, and now has new address now, how do we change the address for the application? 
 

Currently I have an account on USCIS to briefly see the case status. When can I register and track on NVC center? 
 

Thanks in advance