VMware brought in a policy some time ago such that those holding certain Cisco certifications would not have a mandatory NSX training requirement in order to achieve VCP-NV and VCIX-NV certifications - you'd just have to pass the relevant exam and confirm your Cisco certification to VMware.
There was an initial deadline set for this, which had been extended out to January 31st 2016 - VMware have announced today that this path to the NV certifications will remain available indefinitely - great news if you're Cisco certified and you want to get certified in NSX!
Install Configure Manage is just one of the qualifying training courses for VCP6-DCV - at the time of writing you can actually take any of these vSphere 6 courses:
Install, Configure, Manage
Optimize & Scale
Design and Deploy Fast Track
Install, Configure and Manage plus Optimize and Scale Fast Track
Alternate paths to achieve VCP6-DCV are available for those who have previous or other VCP level certifications - you can find those under the Existing Candidate Requirements tab of the VCP6-DCV page.
In terms of exam information and preparation - the links above will give you costs, numbers of questions, amount of time, the exam topics that you will be tested on - for previous version exams this information was found in a PDF known as the "exam blueprint".
The exam pages will also tell you whether that particular exam is "proctored" or "non-proctored". Only the "proctored" exams need to be taken at a testing centre, "non-proctored" exams can be taken from any location/system with an internet connection.
As well as the preparation resources available on the exam pages, the VCP community forum page can also give you some great ideas and help from others, plus there are some great unofficial resources available too: