Can I go to Spain and Work without a Work Visa?

Hello everybody,

I am posting in "Romania" forum hoping someone has been in my situation before. I tried posting in the "Spain" forum but no one seems to reply from there.
Here is my situation: I am non-EU family member of an EU national. I am married to a Romanian national, and I have my residence permit for 5 years now. We have a baby together. Now, my husband and I plan to go to Spain to work for a seasonal job for at least 2 months.
I read through so many things online and one thing I learned that I can travel to Spain without a visa if I am accompanied by my husband. I can stay there up to 3 months but would have to apply residence permit if I will stay more than 3 months. Questions are : Do I need a work visa to be able to acquire my Foreigner's Identity Number (NIE) in Spain?  and Do you really need a Work Visa to be able to work in Spain?
I hope someone here can help me or been in a similar situations like me!