Some great points there Devanur. There is also the option of canonical but the problem is it would mean you're having less pages indexed but one page (the original) would be stronger.

Duplicate content can hurt you but the other side of that is Matt Cutts has mentioned a few times that it wont hurt you unless its spammy, and boiler plate terms you can also normally get away with. For a good nights sleep though its easier just to fix it and know its one less thing to worry about.

Good luck.

Some people will mention keyword density etc. but for me I always found writing for a user is always better as both you & Google at the end of the day are both trying to serve the user. I would estimate above 250 to be a good volume but you can always include things like reviews if your struggling.

More is better but don't blabber, have precise information that's unique.  The best way to to write it trying to sell to the user the rest some what comes naturally after that.

You can view some of the live stores here - http://www.cs-cart.com/live-stores.html

There are some themes here - http://marketplace.cs-cart.com/themes.html

Cs-cart is fully customizable so in general most developers will be able to make any theme you want for it.

You forgot Cs-cart which is widely - I'd take some time to research that as well as to UI is very easy to use and its super versatile

http://www.cs-cart.com/

Don't forget Cs-Cart,  its very easy to use and we offer some very good packages, bit of self promotion we're one of the top cs-cart retailers so give me a PM if you want further details.

did you try clicking on the pen icon to the right ? Should bring up the menu you are looking for.

And, We're writing unique content for each blog. But, I am thinking to use one content / subject for all 4 region blogs.

I found the problem, you were writing well and following the Google guidelines and all was well but you've decided to get a bit more grey hat.It pays off to take the time to write better content for each region.

Well a few things you could try:

• Cross domain rel=canonical - this will stop duplicate but it would only assign rank for one site.
• Attempt to rewrite the article
• Hide it via robots or no index the page.
• Try the rel-alternate however if they are all in the same language I'm not sure if that would work as well not to mention you have 3 regions not 4.

Hope some of that helps.