Dear Khani Hosein,
The 'energy_resolution' is a proxy for the width of the delta peaks that the KPM expansion resolves. The value may need to be smaller (4 times usually) than the features you want to distinguish in energy.
To set the energy resolution you can choose the value at creation of the 'cond_xy' function in your example, or you can increase the energy resolution afterwards by calling `cond_xy.add_moments()`. The `add_moments` method takes either a value of `energy_resolution` or an integer number `num_moments` of orders to add to the KPM expansion.
You may feel tempted to just pass a very small value of `energy_resolution` but the number of moments in the expansion scales as `1/energy_resolution` and the memory and computational time will scale as `num_moments**2`. So adding moments in small amounts until you are satisfied with the resolution is a good strategy.
About question 3, the units of temperature are the units of your Hamiltonian, that is, your hoppings and onsites. You have to rescale `temperature` with `kB` the Boltzmann constant and your units of energy, to get a 'real' temperature in kelvins.
Stay tuned for the mini-workshop, where I will explain the details of the KPM module in Kwant.
https://virtualscienceforum.org/#/quantum-transport-workshop
Best, Pablo