read and write to rbd image with librbd

Hi, I want to write and read from an rbd image with librbd (librbdpy or go-ceph). I got some questions: 1. How can I do a random write/read with it? 2. How can I delete the written data with it? 3. If I want to write with a for example 4K block size should I break my bytes array to 4K arrays by my self or librbd will do it on its own? 4. Does rbd_cache included in it? If yes how can I disable it? Thanks.