For tile solidity on the overworld it's best to block paths with stuff that's already solid, at the top of your screen click maps the tile solidity ro ser which tiles can be walked on and which ones cant then copy and paste them.
As for exits it's on the left side, click on it then at the top it says number of exits, add as many as you want move them around and set the location, all new exits are set to availability false by default you'll want it to be set to true.