wa'alaikum as'salaam,
Mubarak on your wedding brother.
The sister answer all your questions, so just like to add a bit to that inshallah.
For gawah (witness), only two is necessary. There is no such thing as 2 from girl side and 2 from boy side.
Music, band, mixed gathering, etc are all haraam and not allowed. A daff (one sided drum) is allowed on weddings, and that too is mostly for the women and kids to enjoy. Lot of desi weddings have a lot of haraam in it. It's important to avoid this haraam if one wishes blessing from Allah in their marriage.
Lot of this haraam is based on hindu culture and has no basis in Islam, for example:
1. dhood paliyee where the sister in laws give the groom milk to drink and then ask for compensation.
2. jhoote chupaney, where the sister in laws hide the groom's shoes and ask for compensation to return them.
3. breaking of some fruit at the door before letting the groom into her new home - totally hindu custom
4. throwing rice over the couple among other stuff for well wishing, also hindu custom
5. drowery from woman side, this a hindu custom where they force the girl side to give dowery to the man side. There is no basis for such a thing in Islam and we have the hardship it places on the girl side, even to point of taking the whole family in debt for years.
As for video tapes and pictures. There's a difference of opinion on permissibility of photography but majory do say that it is haraam and best to stay way from. As for video making, i would not recommend such a thing unless the person making the video is your own family member and not some professional video company. Too much fitnah has come about in the asia from videos and photography, and it has ruined many girl's reputation and lives because of the evil men in the society.
and lastly, you can visit the following site inshallah to read up on everything related to marriage and islam
http://zawaj.com/articles.html