That's one of those "how long is a piece of string" type questions really. Impossible to give a simple yes or no answer because it all depends on the product and the supplier and that's where research is the only way to get an accurate answer. Sure, nothing stopping anyone from dropshipping into the US from Europe or anywhere else, but it's the second part of that question that requires the research ........ can it be done with a good profit?
In regards to converting currency, mush easier to answer. You can use a site like Link hidden: Login to view to convert currencies based on the most current exchange rate information. Just remember, money markets are volatile and can fluctuate wildly in a very short period of time, so you need to keep a very careful eye on the market if you need to be doing up to date currency conversions.