I wanted to rename lots of filed and folders for my modules, but not to do it manually I made an php script that does this for me. Also I used my IDE to rename code(class names and methods). So just replace root where is the code you want to change file and folder names and do that for strings also.

Migrations and migration api came as surprise to me, really powerful stuff. It can be used as a tool for one of import of whatever content you might have or for continuous import of some data from any endpoint. With core import module, for proper framework I would suggest adding migrate tools and migrate plus modules. 

Whole migration mapping is done in yaml files. So there are few things you need to know when doing custom migration configs.