I'm sure some people have already answered these questions, but the problem is that many of them don't have definitive answers because there is no law or precedent that makes them clear cut, it's going to be down to negotiation. I'll tell you what I know in lieu of someone else who maybe has some detailed answers:
The answer to all of the questions asked by oddcommentator depend on what the negotiations agreeing the legal definition of an post-UK scotland AND the remainder UK
Either Scotland and rUK agree that they are both 'continuing states'
Or they agree that Scotland is a 'successor state' and the UK is the continuing state.
This is the crux of the 'information/disinformation' argument. The UK can't force one outcome or the other, it is in the interests of both parties to come to agreement on what would be best.
If Scotland is a continuing state:
- All UK assets including currency, the Bank of England (the bank of the UK), gold reserves and oil will be divided between the two.
- All UK liabilities including debt will also be divided between the two
- As two continuing states, Scotland and rUK are already members of the EU, if one has to go through a period of red tape to renegotiate their membership, the other continuing state also has to renegotiate EU membership as both states go forward with the same legal status.
- NATO membership would also continue as both rUK and Scotland are continuing states.
Both rUK and Scotland become/remain the same legal entity and both continue within treaties and within groups that they already hold membership
If Scotland is agreed to be a successor state:
- Currency - As confirmed by Darling, no one can stop Scotland using sterling with sterlingisation, this is exactly what Denmark does in pegging its currency against the euro and its economy is robust (my understanding is that this option is actually preferable to a formal currency union). Mark Carney said (as far back as October) that a formal currency union was possible but then UK would dictate much of Scotland's fiscal policy so that negotiation is about balancing the benefits of cross border trade. It's in the interests of rUK to negotiate in their best interests which include balancing their cross border trade, which makes up a substantial part of the UK balance sheet, so it's unlikely in the event of negotiations that they wouldn't actually form currency union because they also want...
- Debt - the debt was serviced by the UK. A successor state HAS no debt, so there's nothing to renege on. Money markets don't have morals and a successor state Scotland would be starting afresh with an economy that generates a surplus. I doubt there would be any problems investing or lending to a new state with the track record Scotland has - the rUK on the other hand is would be even worse off
- EU - there'd be an administrative period to get into the EU - former head of EU says there'd be no problem with EU membership, some with vested interests like Spain say it wouldn't happen. In a realpolitik situation it would depend on negotiations to see what is bluster and propaganda and what actually transpires. Scotland is a solvent nation with a good strategic position, the EU would benefit from a relationship. However, the EU also needs reform, so the benefits of being in the EU need scrutiny and perhaps there's a case for pushing reform of the EU using the Scotland/UK situation in a way to benefit both Scotland and rUK. Norway isn't in the EU and yet is booming and trade between the other Scandinavian nations is barely affected by being out of the eurozone and also by change of currency. The UK is taking a referendum to leave the EU in 2018, so perhaps neither UK or Scotland would want to be in the EU as it is - perhaps there is a better arrangement for the states within the British Isles and Europe.
- Nato - Not all nato members have nukes. It's not a condition of entry.
Neither scenario is terrible for Scotland. The second scenario isn't good for rUK so is it likely they'll negotiate for that, or for the first scenario?
What people say in a campaign isn't what they'll say when the chips are down. This proved by the 11th hour breaking of purdah by telling the people that Devo Max is on offer if they vote no. It isn't, it isn't on the ballot and it isn't on the cards.
In a real negotiating scenario the UK will protect its own interests and go back on every threat on currency and trade. It's just posturing, their negotiating position isn't strong enough.