{REPLACE "; layer 2, Z = 0.120\n" "; layer 2, Z = 0.120\nG1 Z0.2\n"}
Change the 'Z = 0.120' part with the layer height of your second layer. This has to be there to properly insert the move in the right place, on a new line.
Not only was random infill taken away, but the ability to adjust the angle of the top rectilinear infill is now gone, too. Isn't it lovely when a software developer removes useful features from their software?
The only kind of info I can give is it seemed to be when I was quickly changing settings and quickly trying to slice the model. Almost like I was clicking too fast for the program.
Yup, now I get a crash every time I try and slice a project. And then waiting a while, it magically goes away. Maybe however they "fixed" the memory leak causes this.
I've had a lot of crashes with 3.0 doing normal stuff. It would be nice if the simplify3d team actually did their own bug testing. I pay for a product, I'm not getting paid to bug test your software. FOSS has an excuse to offload the testing to its users, commercial software does not.
Random helps because you can lower the density. It's useful when the only reason you need infill is to support a flat roof. The random lines give the roof more places to fall, so it takes less top layers to build a nice surface.
There is no problem... set your exterior infill to concentric, then in the layers tab set top and bottom layers to both be 999, or more if your model is large with lots of layers.