I went to a wedding a couple of years ago, where the groom had accepted Islam (in his teens) but his family remained Hindu. There was a segregated mehndi, and a proper Nikah. The groom's parents and family sat in the audience gave their blessings and did not interfere in the way the Islamic ways of the wedding. In my opinion, if the bride and the groom are Muslim, they shouldn't mix any Hindu rituals because the rituals have religious significance, and reflect on the union of the bride and the groom. The bride's parents not being Muslim should not coerce the Muslim couple into doing something unIslamic especially during something as sacred as a marriage ceremony. Islam gives you permission to disobey your Muslim parents, if they are asking you to do something that doesnt agree with the Islamic faith...so it shouldnt even be an issue in this case.
*there was plenty of naach gana at the mehndi, but since it was all girls (some played the guys' part by dressing up as guys)...i dont understand the concept of muslim girls going all hoochi mama in front of the men at weddings?
but you can't use an example of one wedding you went to as the example that all hindu-muslim weddings should live up to? From what you're describing, it looks like this guy converted on his own accord, not because he fell in love with some Muslim girl and had to...and I think that changes how your parents will react to a conversion. If you convert because your heart opened up to another religion and you did some soul-searching, I think that would be a lot easier to handle than falling in love with a Muslim girl whose parents are now forcing you to convert and wont let you use any trace of your past in the wedding.
with regards to girls going 'hoochi mama,' its all relative...for some, its hoochi mama to dance in front of men while for others, an unsegregated wedding is really hoochi mama. and in a lot of families, culturally speaking, the point of dancing is to show that you're happy for the new couple so the thought behind it is not always 'let me show off for any men in the crowd.'