Please read about Physical Levels and Removing them.

[Reika]

I just put VIT as an example , since is the only proven stat cap along with mnd based on hp/mp.How much does stats really help DoH is debatable, i been leveling bunch of crafts with stats only on vit and str.personally , i see no difference.
hard to say to be honest.

it depends on the difficulty of the recipe too i believe. I find it hard to make simple cotton yarn as a weaver since I have only 16 dex to work off, and that is because it is a slightly higher rank than my weaver rank. Same thing with goldsmith. I failed a good amount of silver nugget recipes in the past, even tho I have Smelting Training and using Guild Facility, all because my dex is too low. I never had that problem with making Steel Nuggets on my Blacksmith, because I had over 110 Str, Smelting training, and Guild Facilities.