So at the moment with fluff groups there are a few things you can control by clicking on an individual piece of fluff and dragging: moving and rotating, with all of the other properties only being modifiable through the sculpting tool. Now, the sculpting tool is great for quickly adjusting large amounts of fluff, but is very difficult to do anything precise with.
So, my suggestion is to introduce a new tool or brush mode that allows you to select individual pieces of fluff and modify those properties directly.

In my mind, it'd be fairly simple (and conventient) to bring over the highlighting from the move and rotate tools and just make it so that clicking on a fluff piece and dragging on the x or y axis directly scales the targeted property (since most of them seem to be number values that can be increased or decreased). Implementing it in this way would allow for a fairly precise level of control, but I'll leave the decision on how to implement it up to the devs. Really, I just want to be able to change these values on individual pieces of fluff without having to use the sculpting brush and don't really mind how it's implemented.

Also: Such a system would likely work quite well for appendage groups as well.