Is there a way to collect interface statistics and maybe create charting?
Can you please be more specific about what you are trying to do? Are you trying to capture data from IGD.PeriodicStatistics and plot it out over time? Or are you trying to capture connection rate/inform rate stats to the CWMP process itself?
graph the differences aka rough bandwidth chart
for bandwidth graphs for each interface, please refer to mrtg, cacti, prtg, polygraphs, etc.
genieacs does not do that