[mmac_]

I agree with the parent comments. You will spend an absurd amount of time making library components, and you can't trust 3rd party. The 3rd party sites are a great starting point to take out some of the grunt work, but you need to tweak them.

Your (cad tool) component library is your most valuable resource, and in my opinion more valuable than schematics/layouts. You have your own proven set of components that you know will work in manufacturing. Even the standard passive SMD footprints need to be tweaked for your specific requirements (ISO, design for manufacturing etc).

In regards to Kicad... great tool for 90% of designs. I would say as a rule of thumb, if your design can be manufactured at one of those online, cheap PCB manufacturers (for say, $10-$20) then Kicad will cover it. Once that calculator tool starts going higher you're probably doing someone more complicated that warrants the more expensive tools.