Please keep in mind that this is only my opinion.
To start my thoughts, I think those very strong attacks shown are only usable after collecting a certain number of stars. In the video, as Kirby collected stars and the top-left corner of the screen kept track of how many he had. These are to reasons to why. Above his lives and star count, were 3 objects that were shaded out. It is possible that when all 3 are flashing after collecting a certain amount of stars, they can be used for his special moves. Very similar to getting a smash ball and using the characters strongest move. Another reason is because when the screen zoomed in on Kirby, you could see a symbol of star on his hat when he used the huge sword and summoned the fire dragon. This could be that he is using the power of the stars to power up his abilities.
Here are my thoughts on the abilities/animal friends. Obviously, you can see that there is going to be at least 3 more powers; cowboy whip, water, and a cannon type thing. Cowboy whip and Water are completely new, but cannon had a volcanic brother in Kirby 64. This is apparently Kirby's Dream Land Wii so it might have animal friend appearances. If this does happen though, it would be very questionable to what what would happen with the special. They would probably be different or not usable at all. As far as regular Kirby alone moves, they might be the same because you see a short showing of sword Kirby doing the slide kick sword attack.
SPOILERS- though these are just thoughts, you might not want to have an Idea of what the villain is just yet. At my first time watching the clip of game play, I saw nothing special indicating the villain. After watching the video a few more times, I noticed a certain enemy. This enemy was the mummy dark matter from Kirby 64! This seen when Kirby uses his sword special the second time. Also, the room with purple stuff following him is suspicious. It could the last world leading to the final boss.
These were my thoughts of Kirby's Dream Land Wii. These thoughts were very thought out carefully, yet I could still be completely wrong. Who knows?!?! The one thing I really didn't mention is that Kirby's life is a meter much like Kirby Squeak Squad. Other than that these were my thoughts of Kirby's Dreamland Wii based off a 30 second video.