Can't pass Dates and use date filtered Charts in Pages?

Can't pass Dates and use date filtered Charts in Pages?

I don't mess with pages very much, but I'm trying to build a dashboard.  I have a search element and several charts that need to be filtered.  I also have a stateless form  for a start/end date picker I am trying to use to filter data for the charts.

Here are the two problems:

1) I don't know how to pass the dates in the stateless form to page variables when the user clicks the submit button on the stateless form. Apparently data access is not allowed for stateless forms in pages so I am lost. 

2) I want to create a chart of percentage of attendance (87%, 92%, etc.) for each name returned by the search. I don't know how to change the Y-axis maximum. Currently the Y-axis is determined by the count of attendance, but the # of sessions will change based on the date range picker...once that's working.  

I can calculate the total number of sessions in the date range just fine if the picker works. However I don't know how to change the Y-axis to a static number or percent. I can probably do the math to normalize each record as a % in the page script, but I'd like to avoid it if possible.