I'll be travelling from Europe to Brazil (Rio). I would like to use this opportunity and see the Water Plant of Itaipu and the Waterfalls of Iguazú as a part of this visit.

Now, if it were in Europe or the US, I would fly to the nearest airport (in this case it's IGU) early in the morning, rent a car there, visit the two sites, get back to the airport and fly back. Possibly, I would spend a night somewhere near to make it less stressful.

However, I have never been to Latin America, I have never driven a car there, I have never crossed country boundaries 4 times in a day (Bra--Arg--Bra--Par--Bra).

So, what are my options and how difficult is this going to be? Especially, my questions are:

0. How difficult is it to rent a car at Foz do Iguaçu International Airport (IGU) and drive it for the ~100 km in the three states?
0. As a Czech/EU national, can I easily do the journey? (Concerning car rental, driving license, visas, ...)
0. How much can you actually see of the Itaipú dam and of the Iguazú waterfalls? Are there any entrance fees?
0. Will I manage things with zero knowledge of Spanish and Portuguese? (The closes I speak is French.)
0. Or, are there travel agencies that offer this combo as a sightseeing tour?

And help is appreciated!