well , i gotta first thank all these peoples who build a wealth of information for people like me trying to get understanding in cnc
Welcome to the forum CHIphload you have come to the right place to find all the info you need your second option is the way to go, start by putting some drawings up to get feed back sketchup, Fusion360 are OK there are plenty of free cad packages around just do a search on the forum.

Please do not buy any electronics (especially kits) motors, screws etc until you have a design almost built.

When you are ready to start, start a build log to keep all the questions in one place.

Good luck with your build.