The Office of International Faculty, Student and Staff Services coordinates all the visa and immigration needs of the international scientists here at Hopkins. They are also good resources for other information. One person to contact at the International Services Office is Enrico Dinges at edinges@jhmi.edu. He may be able to help you further.
The Johns Hopkins International Society promotes international goodwill, sponsors events for internationals as well as for the whole Hopkins community, helps international folks in their transition to Hopkins, and provides many other services.
Article in The Scientist (req. free subscription) on the requirement for good written and verbal skills in English.
Hopkins has some limited financial aid available to help out students and postdocs with the cost of attending the on-site daycare. Check this page for more information.
For help on finding an off-campus child care center, the Office of WorkLife programs helps postdocs by giving them information on other child care options.