Full integration will work since it means a federal state with a single economy. That is automatically a level playing field, all present countries being states within a United Europe with national fiscal control at the centre. The states would only have control over local taxation like the sales tax that US States operate.
Not really! The Harrier was the most over-hyped product we ever made. Although a huge technical achievement, it was useless as a warplane in it's original form since it's arms and ammunition payload simply weren't viable. In addition , it's VTOL capability has never been viable since it reduced the range to uselessness, hence it being used as a jump jet instead, taking off with ramps or using conventional take off and landing.
Very early on we tried to sell them to the US Marine corps but their findings were as I've said above, so they rejected the trial planes while the US continued it's own VTOL research. With that taking too long, the US returned to the Harrier idea and McDonnell-Douglas (later part of Boeing) did a complete redesign, naming it the AV8. That plane was made in various versions, mostly larger and much more effective, more heavily armed and with some range improvement.
The McDonnell-Douglas AV8s was so much better that we switched to the AV8 manufacturing program 31 years ago and the RAF was re-equipped with them, but the popular Harrier name was retained since in Britain it was officially called the Harrier 2, national pride and all that. We have now discontinued their manufacture and the planes we transferred to the US marine corps are their US designed AV8s of course since they don't use the Harrier 2 name.
So the planes we are familiar with were mostly AV8s of various types, made viable by US engineers I'm sorry to say.
