More questions about rust?

Yes, I have a lot of questions, I hope no one minds but if this bothers you, sorry just don't read them. I understand a lot of factors go into the time it takes for iron to rust, but are we talking hours, days, or weeks? (This being for iron submerged in water). And also are iron filings pure, ungalvanized, un-alloyed iron? And finally does the prescence of bacteria (example- in the containter water that the iron is submerged in) change the speed of rusting?