1. You can waive any liability by pushing a contract that puts it back on the business. But I have always read stories in the newspapers where the judge has over ruled the contract saying that it's the contractors responsbility no matter what, even if it's written down in a contract.
2. I know of one local business where the judge threw out the case of slip and fall because the "consumer" that visited the store needs to realize that it's winter, and there will be snow and ice so there is nothing the store can do about mother nature. If the consumer didn't want to deal with the snow and ice then he should have stayed at home.
No in regards to my local businesses here we only maintain two commerical accounts. But those two are always worried about there sidewalks more so that there parking lot. The sidewalks have a zero tolerance for snow, while the parking lot is a 2 inch trigger.