I remember once my father decided that he wanted to combine two smallish rooms in the rather large house we lived in and make them into one really large room. He spent a bunch of time tearing out the internal wall that separated the rooms and it seemed to me like it took half of forever getting all the old stuff out of there after the one wall was removed and the rest of them were stripped down to the studs.
This house started out as an old two story building with 4 apartments in it. When he bought it my dad had the intention of converting it to one really large single family home. I don't know when it was built but it was old enough to have "lath & plaster" in the outer walls. Somewhere along the line somebody had added "blown in" insulation, but it still didn't do much good.
Eventually he got all the debris out of there and installed fiberglass insulation and modern sheet rock in place of what had been there. It was a long slow process because he was doing this in his spare time, something he didn't have a heck of a lot of back then. Add to that the fact that I'm pretty sure he had to learn how to do this stuff as he went along. I am not a hamster, there's very little chance of me personally trying a project like that. Especially when the project I'm thinking of was never actually finished and took the better part of a year to accomplish was did get done.
If I DID try it, I'd probably spend a bunch of time on www.doityourself.com searching out all the details of what I was about to try. After all, knowledge is power and when it comes to home remodeling projects I'm equal to a couple of nine volt batteries. A forum like that would be invaluable with the thousands of articles covering all kinds of several do-it-yourself home improvement topics from how to repair damaged plaster to laying tile.
They've even got a DVD that helps anyone starting a DIY project have a much better chance of getting a project finished.