I have not used any3D CAD Software before, except for minutes playing with Sketchup a while ago and recently, Fusion 360.
I have used Autosketch 10 for basic 2D work quite a bit.

I want to try and design my new Extrusion CNC Router using 3D CAD Software but have some very basic questions.....
I want to use Modular Components Extrusion ( available from Melbourne ) Is this 'Item24' brand?
and Hiwin Rails.

How do I choose a file format to use? Most CAD seem to accept multiple file formats?
Do I have to download all the files I want, preferably, before I start designing and create a new 'Library' within the Software?
Do all the file formats have to be the same?

What is the most popular software to use? Fusion 360?, FreeCAD? Anything else? Happy to buy if needed as long as its not 'thousands' of dollars....lol

I've googled and search here but have not found what I am looking for....

Steve