Hi Henry, I'm no expert when it comes to drop shipping, but I can't imagine why you would need to be a registered business entity in the US to sell there.
You will need a tax id to trade with some suppliers, just to ensure you are a legit supplier, and not just someone looking to save a few bucks.
I have no idea what options are available to you at home to get yourself a tax id, but even if you have to set yourself up as business entity, it should fit the purchasing criteria for international drop shipping companies, but some drop shipping members would be better placed to give you the best advice on that one.
I think you are definitely approaching your venture from a very sensible stand point by not opting for a cookie cutter set-up that will only milk your profits.
If you are going to successfully drop ship products you really do need to source those products from as close to the actual manufacturer as possible. Way too many players can end up involved in a drop shipping web, and each one is milking a little profit as the items get passed down the chain.
I'm no great fan of the whole process, but if you are going to give it your best shot, then I believe you are approaching it with the right idea.
Good luck with it, and I'm sure someone will confirm your tax question soon, weekends are always a little slow!