Please help me so I will be able to make informed decision.
1. Any of you know the ranking of Heriott Watt University, UK?
2. Does the ranking matters for PhD?
3. Can I assumed that if they offer me a research, all tuition fees are covered?
4. I know the US education system (60 credits after masters, 30 course + 30 research)) but not familiar with british system, how the system works if I have masters already in the same field?
5. How much on average the university fee for PhD?

I would really apprecite your help, Thanks

Check this webside
http://education.guardian.co.uk/universityguide2008/0,,2027789,00.html

There's also the SJT (Shanghai Jiao-Tong) rankings, which ranks the top 500 world based opn some complex methodology. It is generally thought to have a bias towards those universities with a strong reputation in science and technology research, and you can also search the top 100 universities by continent. Am not sure if Heriot Watt is on there though.

http://ed.sjtu.edu.cn/ranking.htm

The main ranking for each year is under "ARWU" but you can also look at ranks by subject fields.