I read the previous posts, and there are some good suggestions therein:
* If you have no experience in constructing forms or pouring concrete, then hire it out.
* If you're moving in a year, then patch it.
* The observation about salt is new to me, as I live where it doesn't snow.
Other things to consider:
* Demolition is something you may be able to do for yourself (or hire the kid down the street) and save a few bucks. A masonry blade in a Skillsaw can get you some acceptable joints.
* I've broken up a lot of concrete, and, often, old concrete just gives up when hit with a sledge and a six foot breaker bar. Hint: start at an outside edge and work forward. Dig under the edge that's to be broken and swing away.
* You'll have to do something with the debris. In some communities the concrete must be recycled, and it's surprisingly expensive.