a crafter would probably know much better than others what plants and monster parts to collect than someone with no knowledge, and that justifies why someone with crafting skill would find more ingredients.
Exactly as you say!
If you are McGyver you detect a lot of explosive things around.
https://www.youtube.com/watch?v=tfjhbw7ClzcAs we have some materials usable with certain high skill, it should be so, that you can find mats usable by the current crafter level and one level higher.
So if you have 0 point in Craft&Blacksmit= Tinker then you could find mats for first skill level recipes only and with very low chance.
