Nikaah & Marriage Issues

Iddat for a revert woman previously married to a Hindu

Q: Few months back my very close friend started to like a Hindu girl (who is married to a Hindu with 1 child). Me and 1 more common friend knew about it. We advised him to move away but this girl was separated from her husband (but still in marriage) as this guy used to drink and beat her up. She is not happy rather scared of him. On our explaining, he convinced her and she had converted to Islam. We follow hanafi fiqh and as per our knowledge her previous relationship (marriage) is finished with Islam. 

Is it okay for us to do my friend's nikah with her after completion of iddah (3 periods). Is it allowed as per Islam? There is no way she wants to go back to her husband as she is already separated. Doing divorce will cost a lot in Bhutan (her own country) and she can not afford it? Please guide us if we can do nikah for him and her.

Teaching the children to be transparent with their parents

Q: Please can you recommend what age is appropriate to teach a child their body parts? 

My 3.5 year old only knows it as her private area. And in the shower I only point to all the areas no one is allowed to touch. As she is getting older and ready for school soon my fear of sexual abuse increases daily and I want to know what I should be teaching her and when? 

I only recall my mother ever talking to me about my own body when I became baligh, and I learnt about the male body when I was getting married. Now though, it's different. There's so much more fitnah. And parents that allow their kids to use screens, these kids are exposed to so much more. 

I just want my daughter to get the correct knowledge from myself and her father here at home first before we send her out.

Singing and dancing on the occasion of nikaah

Q: In 2-3 months I'm getting married. We are Pakistanis so in our culture before the wedding day we do an event called Dholki where people get together and sing and dance. I'm trying to avoid doing haram things. 

Is it possible to use drums at the event? Is it only duff that is permissible? The event will be a female only event. Can we dance? At the nikaah event can we use music with only vocals and drums?