set mikrotik ip as dns for client

hi to all..(i use basic setup http://www.mikrotik.com/testdocs/ros/2.9/guide/basic_content.php#12.1.8)
i have a mikrotik ip :192.168.0.1/24.
primary and secondary dns from isp i put it in the ip..>dns..>settings.
clients 192.168.0.x
internet work if i put isp dns on client dns. otherwise it deos not work..
i just want to enable internet for clients but without given them the isp dns
i want to give this to clients
ex: client: 192.168.0.2
sub:255.255.255.0
gat:192.168.0.1
primary-dns:192.168.0.1(mikrotik ip)


2nd: on my network the basic work is on facebook and msn messenger..can i give them priority on other webpages.

3rd: can i disable web cam and voice only from msn
thanks for all

enable remote client requests.

thank you, everything working.
any suggestion on the other questions?