Petrichor03

The black smoke was a man who fell into a pocket of electromagnetic energy. The radiation from the pocket killed his body, but preserved and fused with his consciousness, thereby allowing the man to still exist in a non-/semi-corporeal form and to utilize the abilities of the electromagnetism to build a makeshift body for himself that looked a bit like black smoke.

Was it really brushed off? They explained in Season 2 that the polar bears were brought to the island as part of DHARMA's study of zoology, and that they were using gene therapy and extreme climate change to study adaptation and repatriation in animals like polar bears. This was being done to try to prolong the planet's life.

The writers always intended for scientists to have brought the polar bears to the island when they wrote them into the show in Season 1, and between Seasons 1 and 2 they figured out the minutiae with the gene therapy, etc., which was then revealed to us in Season 2.