For modeling I like Freecad and Blender. Blender is more for general modelling and sculpting, Freecad is more for cad/constraint based creation of precise 3d models. So use blender if you want to create little soldiers or elephants or other more organic stuff, and use Freecad if you want to print a replica of a plastic part or an enclosure or something like that.
There should be tons of slicers available on Linux.