Query - Kalki avatar of Vishnu & Sadhus in India

[Sundeep Dougal]

I hope this is not off-charter. A friend writes:

I need credible and detailed information on:

1. The Kalki avatar of Vishnu

2. Diferent sects of sadhus in India, like the nagas and the aghoris
etc.
Can you please ask the Sanskritologists/indologists you know if
there are any
interenet resources where I can get this info. Or what are the best
books on the
subject, and if they are available in India or the web.

I would be grateful for any help -- instead of cluttering up the
list,  mail could be sent off-list to me.

Thanks,

Sundeep