Been to just one. Here is the recap. 

The deceased was in an open casket in the middle of a room.  Relatives and guests show up. Everyone was given a small wrap with some candy (don't eat it while at the event) After some time has passed, where people can go to the deceased and say goodbye, a couple of relatives gave speeches. 

The closest relatives then left carrying a picture of the deceased, the urn to be used, an umbrella, and left for the cremation. Guests go home/hang a bit and talk.  

I think this took maybe an hour but probably two including the time waiting for all to show up. 

There would be regional differences, this was here in Zhuhai. I dressed appropriately, which for me means suit (it was a sunny hot and humid day) 

If you are close with the family, there might be a dinner.

As always, I think it is not a problem to ask you friend about if there is anything you must bring etc. You should in any case probably avoid wearing anything red. 

Ask about which color is ok and not ok for your clothes... White is a color for funerals in Asia. I'm not sure if dressing in full black suit is the way to go, it might depend on the province.

I'm from China's Ethnic minority autonomous county. We have our special customs. At funerals, we invite relatives, colleagues and friends.  30 years ago we would bring cloth materials to the family and the family would hang the clothes in the spot where the deceased lying (in the coffin).  Now we no longer bring clothes. We bring cash to the family, depending how intimate you were with the family or the deceased. But we always hire the professional team to perform wailing and dancing. I remembered once when I was back in my hometown, the performance noise was so loud we could hear over the mountain valleys. It was a great performance with great mournful song, drums and dances. Actually, people went to the funeral normally enjoy in the show. People talk, smile, laugh..all in a way as if the deceased is still with us and, being a company of the deceased as we know we'll  all be seeing the deceased again one day. The atmosphere is solemn, relaxed, and peaceful.

Thanks guys - I will ask whether I should be wearing a specific colour, pretty sure they are Han Chinese, but would be interesting to see the differences between customs of different ethnic minorities.