Here's a site for you to get a ton of ice fishing info. on iceshanty.com. If you look through all the questions you can ask can be answered on this site. As far at safe ice I like 4" but know alot of guys that will go out on 3" and ice is always thinner towards shore and where there is current. But I will stress do not go out on the ice alone always have a buddy with you at least till you know the waters your going to fish.
Then here is a site to if you were ever to fall through, This is what you should do... You never know, mistakes happen even if someone has 30 years into ice fishing. Its really good to know. It taught me a lot.