She did not brace the building, she lifted it in the air. Torch lured Storm to the parking lot beneath the skyscraper and destroyed the support for the entire building so that it would fall on Storm. The issue stated blatantly that he burned the support for the entire building. That means there was nothing holding it up so Storm had to summon winds in that split second before the building fell on her capable of lifting/supporting the building. Try again.
Here is the scan to the mountain thing.
http://img134.imageshack.us/img134/...uredome14ac.jpg
As you can see, it was no iceberg. It was made up of rock. It was merely coated with ice as many mountains are.
As for Storm breaking Magneto's force-field, it happened in Uncanny 150. He had his force-field up, she summoned her winds, and knocked it down.
Oh, and Storm clobbers Polaris. This is silly. They fought early when Storm first joined the team and Lorna was under the control of Eric the Red. When Polaris can do things like alter the eco-system across and hemisphere, then you can talk Storm vs. Polaris. Otherwise, don't bring it up. Storm can draw upon far more energy than either Polaris or Magneto (when he is not aided by outside enhancements). A fight between Storm and either one of these two would come down to who can utilize most of the Earth's resources. The answer is easily Storm. Neither character has ever moved that much energy as Ororo.