Does mlcp necessarily need a XDBC server or does it work with a HTTP server as well ?
It depends on the MarkLogic version you use - as of MarkLogic 8 (and of course in 9 as well) you can work with a REST API instance as well, there's no need to setup a separate XDBC application server. You can read more about these enhancements in the MarkLogic 8 release notes: https://docs.marklogic.com/8.0/guide/relnotes/chap3#id_46078