Default [Q] regarding upgrade to 4.4.2

hii
i am new to this world of upgrading and flashing . i rooted my samsung galaxy grand i 9082 yesterday and seeking to upgrade it to kitkat 4.4.2 .. I read some in the forums about some stability issue and also dual sim feature will no longer be avalable. please tell me are these true.
please guide me step by step how to upgrade and solve the issues. i really dont know what is cm11 ,what is cynogem mod.. please spoon feed me or provide a link for the same.

regards