Quick Tip: Driven Dimensions | Autodesk Fusion 360

How can I avoid that Fusion rounds my driven dimensions? When I have an expression like for example (6.666667 mm) its value becomes 6.7 mm making my further calculations inaccurate and unusable , that are referenced by the driven dimension.

It would be nice if I can reference these driven dimensions in other features and sketches

some dimensions show "Adding this dimension will over-constrain the sketch. Choose OK to create a Driven Dimension." It would be nice if these show up in the parameters list for further use.