Predicting when things will fill up

I'm monitoring 20+ Avamar servers.  I can get manually get DPA to graph how full they are with a timeframe from 7 days ago to 7 days in the future, and it will project a trend line forward.  That's great, but I have problems automating it.

1. I don't see how to set the timeframe on a scheduled report. I want to see it from a week ago to a week ahead.  How can I set a scheduled report to show two weeks around whatever the current date is?

2. I'd like to filter the report, and just select the nodes that are growing fastest.  DPA calculates a projected line, which obviously has a slope.  I just want to report the slope as a  number, like "avamarxx is growing at 350GB/day", and filter out the top 5 servers (or, better, use the current utilization plus the slope to find the ones that are going to hit 100% within a week.)  I don't see how to do that either. 

Any ideas welcome.