Hi,
What information have you looked at so far to find it unreliable?
I'd say to look at individual universities prospectus's and read up to see what their entry requirements are. You can then look to your USA qualifications and assess to see if they're accepted as an equivalent. If they are, then you can move onto the next stage. If not, you'll need to look at alternatives which get you to the levels needed by each university and it's criteria.
Also research and read up on being an international or foreign student in the UK and all the requirements etc and then evaluate.
As you've mentioned business courses, you'll most likely find that's perhaps one of the more popular areas and places may well be limited etc. You also mention moving to Europe, so for the UK in particular, the next 5-10 years I'd expect will be very difficult for 'foreigners' to move here permanently given the very high levels of anti immigrant sentiment across the UK population. Given the recent vote to leave the EU, there's also an increased risk currently that the jobs situation could worsen should investment into the UK begin to decline. The government here really need to step up as fast as humanly possible to negotiate excellent trade deals in order to 'hopefully' keep investment funds flowing into the UK.
To keep your options open, look to moving to a European country as well and checking to see what entry requirements they have.
Cheers! DtM! West London & Slough UK!