Short term work in Europe

Hello,

My name is Theodore and I am an American. I worked at a vineyard in Napa and the manager of the vineyard (family friend) would like me to gain experience by working at vineyards (for 30-60 days each vineyard) where she has contacts at vineyards in France, Spain, Portugal, and Italy. My work would be in the hospitality side of the vineyard operation. I have been researching short-term employment in each of these countries, and it seems that US citizens do not need a visa to visit these (Schengen Area) countries if following the 90/180 rule, however I would need to follow each country's visa requirement for employment (even with being in each country for less than 90 days).  Does this sound correct?

I contacted VSF (France's outsource company for visa applications) regarding a French visa and was told that due to legal reasons, they were not allowed to give advice regarding the type of visa needed. I have also contacted BLS (Spain's outsource company for visa applications) regarding a Spanish visa, but thought I would post here before I go further. My questions include:

Does France (or Spain, Portugal or Italy) outsource visa applications to other companies that I can contact for information?

Should I contact the embassies directly (not the visa outsourcing company)?

Should I contact an international immigration consultation company or attorney? Any recommendations for an international consultant or attorney for visa information?

Should I post on this discussion board per country to seek visa information?

I'm hoping to receive some advice on the best way to proceed. Thank you.