1. when i search the particular person by name i.e abc it shows presence unknown if i search by email@example.com then it will show the correct status. and another thing is how to get all contact list in lync client .
2. what do you mean by web conferencing and how it is configured and implement
When you have enabled this person in lync account ?. If recent then give few more times. If still it does not work then enable-disable user account and then check ?
Web conferencing is highly integrated with the overall enterprise messaging infrastructure of Microsoft Lync™ Server 2010 and, combined with audio and video conferencing, delivers highly immersive interactions that are simple to manage.
See below link and also you can search lots on google for same.
Read CHM files, See part of conferencing
Anil MCC 2011,ITIL V3,MCSA 2003,MCTS 2010, My Blog : http://messagingschool.wordpress.com