Soldering is really easy as long as you follow all the basics, pre tin everything and have a decent iron with a clean tip. Wire routing and stuff within pedals is way more difficult than the actual soldering aspect to me.
Yep, in my experience, the smaller the wire, the harder it is to solder. I have a PCB amp that I rely on that might be more solder than PCB at this point, but it's been soldered by a man who is a master with the stuff.