Where can I find a sports store selling "Hi-Tec" brand hiking boots?
I'm pretty sure they don't have them in Jordan, your best bet would be getting them online http://goo.gl/Y6Nqd6 then shipping them with Shop and Ship.
Where can I take piano lessons for beginners for a reasonable price?
Try @Sandy for Music or @iPlay Music Center , shouldn't be too pricey.
Where can I find the cheapest HDMI to VGA converter?
I got mine @Virgin Megastore believe it or not.
Where can I find a good American coffee machine?
@Leaders Center has a great selection, including Nespresso.
Where can I find out the traffic fines for my car online in English please..?
I know you can check them online in Arabic here: http://goo.gl/cBIUYf
Where can I buy a power bank ( portable charger,battery ) for my phone?
I'd give @Smart Buy a try, I'm pretty sure if anyone would have them, they would.
Where can I find a place that sells empty polo shirts?
If you're just looking for plain polo shirts, try @American Eagle Outfitters or @GAP they have some nice reasonable ones.