only negative comments I’ve heard about Geo, is the time it can take to obtain certain of his products, and perhaps his keeping you informed. Sounds like a great choice.
I’ve got several “no’s” to your questions. Goodluck with your build, sounding very nice. I’ve always loved the ease of consistent temps of aquariums and sumps in a basement.
I agree, I did the same and concluded no chloramines. However, I did call Naperville and they said at times (did not specify when or why) they use a chlorine gas, so I added a second carbon housing in my RODI system.