Is there any way we can figure out what all indexes are cached into RAM ? I want to know page related stats for individual indexes (# of hits and miss )
You can get overall (instance wide) hit info from the
These numbers are totals seen for the lifetime of the process, so if you want to get a rate or see the trend over time, then you will need to record them periodically and diff the values accordingly. Thankfully, if you install MMS Monitoring, it will do that for you and graph the results.
However, there are currently no per-index statistics available. The relevant feature request can be found here for tracking and voting purposes:
Update: September 2015
The stats referenced above have been removed from the output of the server status command, so are no longer available. However, the referenced feature request is now complete and will be available in version 3.2 when released. There will be an