Do you have emission factors relating to fugitive dust emissions?
Fugitive dust emissions are not well quantified. It is probably worth having a look at the US EPA website as they have some information although these factors are subject to a variable degree of uncertainty and frequently require large assumptions to be made.
What is the emission factors for open burning of rice straw and other agriculture waste?
A CO2 emission factor does not exist as the burning of agriculture waste releases recently sequestered carbon and therefore there is a neutral balance.
Are there emission factors for biomass boilers? Given the variability of fuel (e.g. woodchip) is generalisation possible?
The emission factors can be found here. But you are correct - emission factors are dependent on the fuel (biomass covers a large variety of fuels in a variety of physical forms), the combustion technology employed and (for larger facilities) the type of emission abatement.
How do I interpret the population emission units. Are the emission rates expressed as units per 1000 population per year?
The emission factors based on population are UK average factors taking the total emission and dividing it by the population. The units are as annual emissions (e.g. per year). | 
