Zivush - 5:34 am on Oct 14, 2012 (gmt 0)
Sorry I missed your post,
I think, the reason you haven't received answers from anyone is because it's controversial.
(1) + (2): Bolding a paragraph to highlight a section of your content is a good practice IF you want to regard this section with high importance over other paragraphs of the content.
However, look at it from a machine side (Search Engines algorithm), when doing so (systematically), the content become unbalanced. The algo may contain some code to protect itself from tricking it against such content structure, especially when it contains targeted keywords in bold. It becomes a risk. They may call it over-optimization or suspicious content or whatever.
I'd rather treat it this way: If the paragraph can live without making it bold, don't put it in bold.
(3): It is also true in case # (3). Why do you need to tag <h2><strong>Text here</strong></h2> instead of <h2>Text here</h2>?
Don't let the algo push the wrong button and just try to be on the safe side :-)
A site with too many similar pages may be categorized by SE as machine-made site (an auto-content site).
Such sites are the target of Panda.
Therefore, try to structure each page slightly different from the rest.
Hope I helped.