I am sorry for your loss it must be a difficult time for you, We live in a village full of old people, so are used to this sort of thing. Our advice would be, do exactly as you would in the UK. If a card would be appropriate there, it will here, If a visit would be better in the UK, it would be here to. Hugs are not an issue? Go for it. It will be appreciated more than staying away.
French funerals tend to be a little less formal than in the UK, so don't be surprised to see people in Jeans and T shirts. We always wear traditional UK funeral clothes, so I would wear a dark suit, white shirt and black tie. Jane would dress in grey with no colourful attachments. The French have always commented their respect for us doing that. In fact at the funeral for the mother of the people we bought our house from, Claude mde a point of thanking us for the effort we had put in.
Expect the service to be about an hour. At the end of the service, you will be expected to line up and pay your respects to the coffin. Don"t worry, it will be firmly closed by then. Catholics commune as they pass the coffin, but it is not a problem if you are not. As you pass the coffin, I suggest you place your hand on it, close your eyes and say a little something for the person you have lost. Don't feel rushed, I have known people rest their hands on the coffin for 15 minutes! So pay your respects to your friend in your own time, and don't be afraid to help the little ones get through this. You will gain much respect for helping them. They must be devestated. Has your friend a husband? If so, keep a watch out for him too
Hope this helps
Will be thinking of you