In the desert cave
You can find a bunch of them in the cave on the second island. They will show up in random places to so keep an eye out.
In the cave, far into the forest there is a tree, rather spooky with Jack o'lanterns hanging off of the branches.
you go to the train station thingamabob and when you are in the cave press prospect. search around until you have the option to dig. keep diging until you find the stones
you can find ghost essences on a scary tree behind your house or in the desert in a cave or in my Sims kingdom you can find them by fishing behind zombie Carl's place hope this helped :)
I find My Sims Agents wii is better, but it doesn't take very long to beat.
cutopia
the cowboy island
the uncharted isle
you unlock them last
no, no u can not
if you've got wii you'll have an explore around and try to find out if not and you haven't got a wii, like me then i cannot help sorry :( helpful katie- To be honest I dont get what you mean because im on sims 2 castaway on the wii and ive had 6 sims but i dont know about any other sims games for the wii