Although you may be approached by certain people to change money illegally, there is no real black market in India as the Rupee is fully convertible. Those arriving without the proper vaccination certificate will be quarantined for up to 6 days. The actual vaccination should only be considered by those planning stays of more than three months in unsanitary conditions where no medical facilities are available. Malaria is prevalent in the whole country below 2000 meters altitude. In general, avoid walking around on your own during night time.
Terrorism is widespread in certain areas and sometimes tourists have been targeted.
There have been shootings in public places in Srinagar. In all major Indian cities outbreaks of communal and inter-caste violence can occur. Government response can be in the form of imposing curfews. Political rallies and demonstrations are to be avoided, especially around election time. Don't travel out of major cities at night.