Hi, we use Marzipan in UK to cover fruit cakes, mostly. BUt I know there are decorrators who use that to cover sponge cake as well. I don't do except requested by the customer.
I knead it same as fondant, but not too much and no crisco. If you over knead, it will be very oily. You have to roll it out on powdered sugar. And cover the cake as you normaly would.
YOu also can make figures from Marzipan. But to be honest with you I haven't tried it myself. You can colour it as well.
Here is a link where you can get all the info about Marzipan.