Pods will exist in a tank. they are very small and hard to see. after lights out look for little white hopping dots. They are usually one the front glass. They are in there if you have LR and LS. For the "thing in the back" to count as a fuge it would have to have LS, LR and macro algae, as well as a light to grow them all.
The reason for the fuge is so the pods have a place to live in peace and breed. Every time you disturb the fuge, some pods will go into the main tank area andget eaten. So the fuge is like a back up source.
I would say skip the scooter. 24 gallons is really small, and the pods would be wiped out in a mater of months, if not weeks.
However, if you can find a scooter that will eat frozen foods, and you have proof of that, then that would be fine. If you dont have proof they eat frozen, dont get it.