Pay package to work in China

Hi all, need some advice. I am in my mid 30s, married no kid yet and are planning to have a baby within 1-2 years.

I am currently working as a middle management role of a healthcare sector mid size company back in Singapore. I was recently approached by an "ex boss" who would like me to join him in his new company (Big healthcare MNC) and be sent to China as an Expat. What will be the kind of expat package i should be expecting?

Is it reasonable if i ask for 30-35% higher based salary (assume tax equalized). If i were to change job in Singapore, i can get additional 10-15%. So i set a premium of 20% for the inconvenience and hardship. In addition to accommodation and utilities allowance, I would also like to ask for 1 flight back home per month (China is quite near to Singapore). 

Does the above request sounds reasonable? How about living expenses? can i ask for it?