This varies by country; in Greece, as I understand it, we will not be allowed to buy e cigarettes or e liquid from outside the country. I don't know how that will be implemented, though (will they confiscate?, fine?, just throw on an extra customs charge? Will they be zealous or lazy about checking every package? I don't know!), so I guess it's just wait and see how it will work here.
Here's info for Romania that might help you?
	
		
	
	
		
		
			Will EU customs stop our shipments with vaping hardware ?
What can we do if EU customs confiscated our packages ?
		
		
	 
There won't actually be any separate EU customs body examining packages, it will be your own country's customs people who will handle this according to the laws locally.
From 
a Reddit thread, the actual EU directives that all members have to abide by are these:
- 2ml tank capacity
 
- Notification for all ratio's and nicotine levels available costing individually based on country
 
- Limitation to 20mg strength
 
- Limitation to 10ml bottles
 
- Leak free filling (this looks to outlaw the vast majority of refillable and all rebuildable products, to be replaced by e-cigarettes with the same generic and standardised filling mechanism).
 
- 6 month wait period from notification to sale.
 
- Advertising bans
 
So there's nothing 
from the EU that says you can't buy hardware from China/US etc. (except for tanks above 2ml capacity, I suppose), but countries are applying their own specific, separate laws about that.
All of the above ^^^ is just my understanding, so far!