La unión hace la fuerza

Yes, but usually in specific contexts like teamwork, sports, or community efforts. It's not something you'd say every five minutes.

Absolutely. It's formal enough for a professional setting, especially when closing a message about a collaborative project.

In Spanish, proverbs often use 'hacer' (to make/create) to show that the result is an action or a construction. Unity *creates* the strength.

In the proverb, you must use the article 'la'. It makes the concept feel more universal and complete.

They understand it perfectly, though they might use shorter versions like 'Juntos somos más' on social media.

Not a direct one, but 'Hacer piña' (to make a pineapple) is a slang way of saying 'to stick together as a group'.

It's a bit weird. It's usually for larger groups. For couples, people might say 'Somos un gran equipo'.

'Divide y vencerás' (Divide and conquer) is the most common antonym.

Yes, the wording is identical from Spain to Argentina.

People will understand you, but it's not the standard proverb. Stick with 'fuerza'.