Is it possible to use the Forena module in conjunction with the Flot module?
I'm not aware of a way to use the Flot module in conjunction with the Forena (disclosure: I'm a co-maintainer) module.

About "Virtually any JavaScript library may be used with Forena ...": have a look at the feature request # 2364427, especially these comments in it:


Comment nr 7, which is about a module for using Forena data with the d3js library.
Comment nr 15, which is about a related sandbox project.
Comment nr 18, about the D3 strategy.


Another approach is to write your own "renderer", as a variation of the FrxSVGGraph renderer (which extends FrxRenderer), and which is how the current support for the PHP SVGGraph library is implemented.