Electrical – DC/DC converter from 9V to around 180V – LTspice simulation

To answer my own question: it seems LTspice requires text files to be saved with Windows Latin 1 code page, CRLF line endings. I'm using Wine on a Mac, and my text-editor saves as UTF-8 by default. I'm guessing LTspice misinterprets the UTF-8 µ on capacitor values as something invalid, but confusingly doesn't throw an error message.

You will never find an absolutely complete parts library from any vendor. What you need to do is learn how to use the library editor of your tool. There you create packages and symbols that you can place in your schematic and layout, based on the datasheets from the manufacturer.

As far as simulation goes, there is no complete/unified tool for this. You'll really only find SPICE models for basic parts, such as transistors and diodes, and sometimes for bus drivers (like pins in an fpga). You'll use a SPICE simulator for doing timing and frequency analysis for that kind of thing. For code, you'll use the simulator that usually comes with the development environment of the processor. For VHDL/Verilog, you'll need a simulator such as ModelSim for that. And for simulating transmission lines for signal integrity, there are also separate simulators that take in geometric and materials data, and also the bus driver models I mentioned before.

So the idea of simulating the whole design in one go is not really feasible, unless its scope is very narrow. What you end up doing is simulating each subsystem separately in its own suitable testbech environment, and then join everything in the pcb. Once a prototype has been manufactured, you can test, probe and debug the system as a whole.