I am looking to buy a camera which is relatively small, that takes very good video as well as photos. I like the Sony Rx100 III but there's no audio in, and the lense is not interchangeable. I want to be able to add a microphone to the top as well. Please help!
You could consider the Fujifilm X-E1 Mirrorless Digital Camera. I don't know how good it is but it does have interchangeable lenses and the option for an external microphone (according to the specs).
The Sony Alpha 6000 does have an option for external microphone (ECM-XYST1M) which will attach to the hot shoe. The microphone sells for around $140. It does not appear to have the 1/8" port for external microphones.