Yahoo France, Japan, US, India

Is there a reason why each country has different serps?

One of our site ranks 1st position to 2nd position for all other countries beside the US Yahoo.

It has been said that if you have back links hosted in other countries that this will be the reason why you rank higher in those countries.

All of my backlinks are hosted here in the U.S. but still can not get to the top 5 positions.

Any suggestions or thoughts on this?

Could Pay per click increase backlinks?

Can this also favor you over other sites in search results?

Somthing in your site tells yahoo that the contents of the site is more relevant in France, Japan and India than in US. Else, there might be more competition for that particular keyword in US than in France, Japan and India.
Anyhow, if your site is hosted in US; you may not have any problem and will have to be patient and build back links till things settles down.
No. Never.
No. Never.

The hosting part makes no difference although by looking at other aspects Googles algoryth seems to know a site's target by words in the text, possibly registration address plus the same criteria for the backlinks.

The algorythm for the non US yahoo may not be necessarily the same, it some cases you might even look at the entities as seperate companies in whole that just use the same database...