I'm not really sure about how he survived, though I have theories, but I'm pretty sure where he stayed after faking his sucuide. He stayed at Angelo's. least, I'm pretty sure he did. Come on. Angelo pretty much said he'd do anything for sherlock as thanks for getting him off a murder charge. This should probably include housing the dude after said sucuide. And I think the really paranoid assassins- heck, Moriarty probably asked them to- would be checking to see if sherlock left the area. So as a precaution- and where else better to stay hidden than in plain sight, preferably inside a house?- he stayed at Angelo's. Angelo could probably keep sherlock in the know while hidden at the same time. No one would be suspicious about extra food or ingredients as it would be put down for the restaurant having more customers to feed. He could also where disguises and be the washer boy as payment for staying, once he annoys Angelo too much or something. Either that or he worked in a bookshop as an assistant or owner. Probably the cashier.
as for how he survived: Mycroft provided the help and resources through Molly. Irene delivered them to her. Lestrade had to be in the know, to lead the investigations and tell everyone that it was real, in case anyone else doing the search found out that it was a fake or asked unwanted questions. He probably won't be told much, just that sherlock is still alive or something. Molly will provide fake statistics of his death as evidence, and Lestrade'll back her up. They won't be able to tell John, though. Mycroft will provide the resources needed for the plan to work- Whateverdrugs or disguises sherlock needs, the fake body, information for Molly, etc.- hell provide all of it. H might even provide Lestrade the authority for the investigation by appealing to Lestrade's higher-ups. But he'll definitely stay out of the picture and into the furthest background possible. Irene would bring all the stuff Mycroft needs to give sherlock and smuggle it all to him, then leave to be in hiding again. Sherlock was probably at his wits end or organised the whole thing. If he was at his wits end, he landed on the surprisingly convenient mattress/net/whatever and was knocked out by the people helping. They then add more blood- taken from the blood bank sherlock stored his own blood in- and tape the ball on him to stop his pulse. The E.R people who're mycroft's people take him in. They bring him in to Molly, Irene s,gurgles him out and he lives in Angelo's /whoevers place till season 3. Another option is using a dead body. Provided by Mycroft, changed to look like sherlock by Molly, then used as a decoy to convince John and any other assassins or something.
If he did plan the whole thing, he lands on mattress,takes in knockout gas and gets the ball stuck on him to stop heartbeat. He gets smuggled in by Molly, out by Irene, stays in Angelo's house to keep an eye on John and works in a bookshop. Or they just use a dead body provided by Mycroft and changed by Molly. Either ways, he's known as dead.