1. If the Lizard is able to walk past the sprayed area, that means the repellent effect is gone and you need to recoat it. It is suppose to repel the lizard from coming near as you can read from the feedback given by the customers.
2. Same as point one. It will only die if you spray directly on the lizard.
3. Lizard will avoid the area you sprayed.
4. If you spray directly on the lizard, there will not be any ants around it because there is chemical around the lizard, repelling the ants as well. It will dry up like cuttle fish. Of course, if it is many months, there might be ants eating it as it is rotting there for so long. It is just like all living matter, after long time when it dies, an awful smell is being emitted. If you notice a weird smell quickly search and discard the dead lizard. It is not toxic to us not to worry.
I hope I have answered your questions accordinly.