Those are some significantly different sized animals there. Are you positive the big one is a male?
Unfortunately chinchillas cannot be trained to poop in one place. Their digestive systems are not exactly made for control, however, urination is different. Typically chinchillas will urinate in one place in the cage and not go outside of the cage with it. They typically do not urinate on shelves in a cage that is properly set up. I hate to say it but your cage has some problems (I'll get in that later).
Raisins are okay to give as treats. I know not everyone agrees but it's common practice and you won't more than two in a day. I don't recommend them though as there are better alternatives like cheerios, no more than 4 in a day. My philosophy is don't give treats unless you have a very good reason to do that. They only reason I can think of is trying to tame a very wild pet who is afraid of you. The more I research on this subject the more I think treats are generally not a good thing for chinchillas and interaction is what they need most.
I actually use the same cage as you but I've modified the floor. I should post an article on this but it require some skill in fabrication of wood and metal. For the FN-182 cage there are aftermarket metal trays available online. The plastic is going to be chewed on by your pets and they will likely escape as others have reported with the same setup.
Another possibility is to use fleece lining, which is like blankets, and perhaps those blankets were designed for the cage, in which case they should washed and reused or order some new ones. Fleece is not ideal in my opinion but owners have had success with it.
The metal flood pan is ideal for you and it should be used with pine chips as bedding. I wish I could refer to a local source of these but the only one I know of is Bass Equipment (
www.bassequipment.com).
If you're interested in building a wood floor I can give you some pointers. You'll have to staple a wire floor to a wood frame and insert it as a panel. Then you'll have to build rails to accept one of the plastic trays to go underneath the wire floor panel and use an absorbent pad like a puppy pad over it. The chins will urinate through the grate onto the pad. You'll just remove the middle panel and add some more shelves to your cage. This is how I have it in mine.
It is not good practice to have plastic in a chinchilla cage that can be gnawed upon. Plastic can be deadly if enough is ingested. Wood and metal items are ideal.
One last thing I don't understand is why there are two water bottles. It might be better to just have one in there so you don't have to maintain two. With any water bottle check it to make sure it dispenses at least once a day in your routine.
