Advice for a family vacation in Okinawa on summer?

Hello!

We were planning a trip to Tokyo when we thought it would be a shame not to see more than just the city in this beautiful country. We wanted to see the beaches but also the nature. Having only a month's vacation in the country, I decided that Okinawa was the right compromise. We'd spend 2 weeks in Tokyo, then 2 weeks in Okinawa before returning to France.

I started looking into beaches and swimming on Okinawa Island, and it turned out that the local wildlife was going to be a problem. I did, however, see that some beaches have protective nets against jellyfish and other venomous species. We're looking for a carefree family vacation, so I have 5 questions:

1. Are the protective nets available at this time of year? (we'll be there between the end of July and the beginning of August).
2. Will the nets be a sufficient safety measure, or are there other arrangements to be made?
3. Is Okinawa the right place for this type of vacation?
4. Which beaches would suit us? (So with a large enough safe swimming area, preferably. We'll have a rental car, so distance won't really be a big problem).
5. Do you have any ideas for other family activities? Or places to visit?

Thanks in advance for your help !