Hello,
is possible to have custom dialogs (without dialog plugin)? Current state: user have to click Image button, then click Choose at server button, choose image at server, confirm selection, confirm dialog.
What I am looking for is Image button - > Custom dialog (that returns required values for editor) - > Back to Editor. Basically just one dialog instead two.
I need completelly bypass dialog plugin since it cannot meet our cms requirements. Is that even possible?

Yes, you can create a plugin
Yes, you can create a plugin that uses your dialog and does whatever you want.
And is there a tutorial for
And is there a tutorial for Plugin authoring in CKEditor 4? I was able to found only for version 3.
That same tutorial should
That same tutorial should work, the differences are minor with regards dialogs (mostly additions if we forget for a moment the new ACF)
Anyway, here's the documentation for v4: http://docs.ckeditor.com/#!/guide/plugin_sdk_intro
found this plugin works for 4.3 version
here have a try
http://ckeditor.com/addon/custimage