If you are looking for CRUD operations on external data, then you can have a look at this post
See if you can adjust this with search and select on the case type. The post mentions about the landing page approach. But you need cascaded filters which currently seems a bit difficult.
Also a part of your requirement (kind of linked) was asked by another community member which might interest you or give you some ideas to get the juices flow in the mind
Your requirement is not straight forward, so you might have to stitch multiple things together to get closer to what you need.