You can use sawdust as a filler for epoxy but sanding dust would be better. Sawdust in epoxy leaves a a very rough surface. Sanding dust will be much smoother. If mixed to the right consistency, it'll still flow. Heat the wood if you can before adding the epoxy. Pour in a bit of unthickened...
The angles are as given in the image you supplied. Tell me how thick you want the pieces to be and the length of the longest dimension. That is, do you want close to 6 inches? Or maybe some other dimension?
The last 32-bit version of SketchUp was SketchUp 2016. Trimble did not drop 32-bit support right after purchasing SketchUp from Google.
You can get the 32-bit version of SketchUp 2016 Make from https://sketchup.com/download/all
As for the online version, it is called SketchUp Free. It runs in...
You would need to take off more than the thickness of the mating piece. It would be the length of the angled face. If you'd already cut the angled face, though, you could mark off the thickness of the piece from that face and trim those pieces again.