1. Time will tell whether this is "a seriously wrong decision" - remember how Zagaro treated Romario before the 98 World Cup? Besides there are far too many alternatives to Ronaldo.
2. Noted that Dunga is managing Brazil, a country whose second rank players are still much better than most countries' first choice options. The bench depth is just too sufficient for them to choose only the second rank players while still they are going to succeed.
3. 100% - he will be fully responsible of course.
4. Heaven knows. Romario set an example that he has never been recalled to the national team again. If miracle happens next season, where Ronaldo plays superbly for Milan in Italy and Europe, he may still have a glimmer of chance to be recalled by Dunga.