agreed. file extension has nothing to do with SEO. .php, .html, .jhtml, .xhtml, .jsp, .aspx, it's all the same for SEO.
Does not matter, they "all" render HTML either way, tho server side programming languages are much more powerful than pure html written files.
also php is better due to the mod^rewrite and not only that, but like someone else mentioned easy to change
Use any platform PHP or HTML but keep in mind when make url structure for your website. Its is very necessary in optimization process for any website.
I think that as long as the pages have unique, well written content on them, they better, regardless of the page extension.
They may rank .html higher than .htm since .html is a dynamic extension whereas .htm is regarded as static content.
Extension doesn't matter. Header directive "Content-type" matters. For .html, .htm, .php, .shtml, .txt Apache returns "Content-type: text/html", so they are equal for search engines.
You can use it to expose your php files as if their extensions were html if you were worried about it.
both the same. lots of webmasters said that static html file would be good. but treating php file like html would be better using mod_rewrite.. use php to ease the implementation.