I started out with that same kit, it gets the job done for starting out but the resin is really thick compaired to some of the other brands and has a lot of fumes, just make sure to have lots of fresh air avilable. It also has a fairly short working life so that means you'll need to get your mixing and pouring done quick.
Biggest thing to remember is that you'll need some practice and don't give up. I went through my entire first batch of stuff before I had any good casts, had much better luck when I changed brands. (but I also didn't have anyone helping with a forum like this one)
The Vaseline you can heat up in a spoon and a cigarette lighter, as it's warmed it'll become liquid allowing you to brush it nice and thin across the mold face.
You probably are better off using the spray release
http://www.smooth-on.com/Release-Agents ... index.html You'll definately want that for when you are doing your casting as it'll help your molds last about 4-5 times longer.
The baby powder helps keep bubbles from sticking to the mold when you are doing the resin, you put some on and then take all the excess so that only a very faint dusting remains on the mold. When you pour the resin it helps break up the air bubbles that get trapped in the molds.