1. What about the tens of billions of smuggled good making it's way into the UK? A border works both ways, you know. The only thing the Eire will loose forever with the UK will be the open border.
3. The EU cannot boot out any other country. Countries may leave if they wish, but can't be kicked out for whatever reason. Otherwise you can be sure the UK would have been out for a long time now, always wanting a cake and eat it too for decades. The Uk got exemptions, rebates and whatsnot, and yet they are still unhappy and bickering all the time. There were times where I would have loved to be in the European Parliament just to tell Cameron at the time to shut the fuck up for his ridiculous demand of the day, and yes, including the F word. You'll understand that many Europeans just think "Goodbye and good riddance you ingrates" when it comes to the Brexit.
In any case, wtf about all that talk of smuggling?
Besides, if the UK crashes out, that also means no deal on the Irish border and thus a hard border will be unavoidable there, and all because the UK parliament can't stop bickering with themselves for 2 seconds. Seriously the parliament is so broken that whatever the EU would offer by now, it would be shot down in parliament even if it would be better than what the UK had during it's stay in the EU. So forget about any backstop, that won't happening, and the UK should take all the blame for that.
1. I very much doubt that. The UK has a leverage because it has the power to unilaterally import whatever shit it wants and if Ireland doesn't want to be responsible for meeting EU customs requirements then it's as good as single market access but without many of the downsides of membership for the UK. The EU single market by definition is a very protectionist and developing market when Southern Europe struggles very much and Eastern Europe is in it's infancy so imagine for a moment what the instability of being out competed by far cheaper goods would mean to them ... (we are talking about rising deficits due to capital outflows in places with relatively high interest rates)
3. Article 7 and I don't think it will matter much if the other 26 remaining EU member state won't tolerate Ireland not cracking down on smuggling ... (EU needs to cut Ireland out of the single market and customs union just in case it doesn't install a hard border)
A hard border CAN be avoidable but it means Ireland quitting the EU single market and customs union plus the EU is threatening Ireland if it doesn't take action ... (I guess there are *cracks* within the 'solidarity')
If Ireland DOES want to go the hard border route then they can kiss their chances of reunification goodbye ... (GFA stipulates that Ireland must meet it's end of the bargain in order for Northern Ireland to hold a sovereignty referendum)
Leo and Ireland especially must pick between having their pride (reunification) or it's source of wealth (EU single market) ... (the DUP will make life hell for them)