1. Hiruzen didn't "barely help" Minato.. he was the whole reason Kyuubi didn't wreck the hell out of Konoha. Then that could've potentially disrupted his fight against Obito. However, Minato KNEW the third Hokage was there to take care of things, hence why he took care of Obito.
So Jiraiya has done nothing besides train people, who went on to become OP ninja by themselves.. hes a good trainer cool. He still didn't save the village. The book again, was used by Naruto.. its entire relevance in "saving" the village is because of Naruto Uzumaki who defeated Pain.. and would've killed Nagato if he wanted. Nagato wasn't moved by the book, he was moved by Naruto Uzumaki. ... if you are trying to start the whole "indirectly helped" thing, then start it for Tsunade as well.
2. No he wasn't, Hashirama didn't decide who the first Hokage was, the villagers did.. he had zero chance in becoming the first Hokage, due to the fact villagers didn't want him.