Is there any info for beginner coxing on actually how to steer, i.e. little movements, at what part of stroke is ideal etc ?

Sure thing, you can get all the answers from Coaching the Coxswain ebook by Chelsea Dommert.  It was written by an experienced cox who got frustrated at the lack of tuition coxes got from coaches.  Her approach is to guide the coach (who has never coxed themselves) on the best way to instruct and guide a cox.

There are tests at the end of each chapter so you can self-appraise or run tests for your cox on how skilled they are).

Here is an extract from Chelsea’s book which as a Rowperfect reader you can read for free.

A guide for rowing coaches

And Coxmate has a great free email series for beginners written by expert Coxswain Andy Probert. Top Tips for Coxswains.  Coxmate also has a heap of Coxing Resources and writes a helpful blog.

British Rowing have just launched an online self-training tool for coxing

http://www.britishrowing.org/knowledge/online-learning/coxing/introduction-to-coxing-steering/