I have to ask another set of these data, but for the mean time, i need to proceed with these data as I need to get the statistical summary of the returns which were not in these raw XYZ format.
I would also suggest using LAStools. It has a wide range of 'modules' to allow you to analyse and query your data or to extract variables that you want.
It is mostly OS, meaning that it can be used for research etc. but not commercially without paying for a licence. There is also the LASmoons program, where you can write a bid for a full user licence (for a short period of time) to help you with your research.
I feel LAStools is best integrated into other software eg ArcGIS or similar - there is a toolbox available for this.