Advice needed - ebook writing

[Paul Mac]

I intend to write quite a few ebooks this year - some will be from material available in the public domain, others will be ones written from experience.

I have several areas of expertise - for example health and wellness, starting home businesses, and a few other diverse areas.

My questions: do I keep the same author name for all, or do I use a pen name for each different area or expertise?

What are the advantages and disadvantages of using the same or different names?

How do i build myself up as an authority of a subject if I am using pen names?

Your advice would be much appreciated!