1

No idea of a Micro. Buses go daily from Foz do Iguaçu to Rio. But they are pricey. You could get a cheap flight and do it cheaply.

2

Definitely agree about the flight from Foz to Rio. There are a couple of low cost airlines that do that route and if you buy in advance it costs probably less than a comfortable bus journey. And takes about 18-20 hours less.

In terms of Rio, I would recommend going to Santa Teresa and getting there a bit early, around 10ish. It looks like an empty bohemian / art deco neighbourhood and you wonder what the fuss is all about, but then around 11.30-12.00 the crowd comes in and the place is heaving with humanity - artists and tourists alike.

There's a few good places to eat there as well, and some of them with a brilliant view.

I have never seen anything like that in my life.