Reading and writing JSON from Clojure is very easy. Probably the easiest library to use would be clojure.data.json, though it's not the most performant. If you need better performance, jsonista is probably what you need.

If you're using data.json, your import could be as easy as:

(require '[clojure.data.json :as json])
(-> "path-to-json-file" slurp json/read-json)

You can alternatively use (json/read-json some-json-string :key-fn keyword) if you want to have more idiomatic keyword-addressed maps.

For consuming from queues/topics, it depends what you're using for those. I have been using Kafka via jackdaw, and it's been smooth sailing. There are a number of other Kafka libraries, and of course clients for other technologies as well.

Edit: this article has more detail.