It's ok, you don't get any added advantage in knowing where the spawners are: I use CAW to check where all the spawners are when I'm getting to know a world. If you have a working copy of your world, go to where the spawners are listed down the side, and right click each special spawner and select 'find in render panel'. It will take you straight to it.
The main possible advantages to using your own world are: too many special spawners (if you put too many in compared with EA worlds), world adventures skilling objects, any objects not availabe in an EA world. You're pretty much right to use all the plants except the money tree. Some worlds have an omni plant, Barnacle Bay has an abundance of life plants, and I think all worlds have at least one death flower.
