The h1 should be the primary keyword phrase and visually be situated at the beginning of the page in the header.
h2 tags should be descriptors of the h1.
h3 tags should relate to their parent h2 tag.
I do not think the amount of h2 - h3 - etc tags matters but the semantic hierarchy must be maintained.
In the visual presentation, the text inclosed in the h1 tag should be the biggest on the page, with the h2 following as 2nd largest.
h3 and regular text bold are the same size.