Hi Sandra,
Congrats on the move. I was in Montezuma in January – really cool place. I do know the beach right in the heart of town is good swimming. I’m not familiar with the safety of the other beaches or rentals nearby. But I would suggest you try some local real estate folks to get their take. This is one agency I know that is active in town: http://www.tropisphere.com/area/montezuma/
You could also stay at a hotel or hostel for a week while you ask locals and local expats. You can often get better deals in better spots through word of mouth. A great place to meet expats in Montezuma is the Saturday morning farmers’ market in the center of town.
VRBO.com and airbnb.com are other options for usually short but sometimes also long term rentals.
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