There a lot of HVAC software available. It will depends on the amount of capital you are willing to spend on it.
List of Software i know that are widely used are:
1. HAP
2. HEVACOMP
3. IES
maximum run for the RS/RL depends also in the location of the condensing unit of the multi-split. You should contact your manufacturer about this, i believe mitsubishi units can handle 20m vertical & 30m horizontal pipe with the location of the condensing unit at the bottom. If the Condensing...
I agree with cdxx139, you should check the code to meet the requirement. for your questions,
1. Yes, you should be running the main intake exhaust & supply fan at normal conditions.
2. CFD are needed for us to know if the location of the jet fans will perform as intended when there is smoke /...
