While the economy of the war losers is an extreme example, it is also my personal observation that countries with highest inflation rates are poorest. Japan is the only significantly deflationary economy I've visited and it seemed to function fairly well in comparison.
Yes, but I don't think that Japan is a good example to hold up.  Their government is in debt to 180% of their annual GDP.  They are actively trying to devalue the Yen, in order to encourage exports.  So is basicly everybody else, but only the Chinese do it 
well.  The stability of Japan is, I think, largely a byproduct of their culture; and one I don't think will survive their demographic peak in the near future.  I can't predict how it will end, but I give high odds that their social cohesion is going to be tested as their aging population is increasingly dependent upon a (relatively) shrinking working age population.  The same can be said for the United States and Europe, but Japan will certainly get there first, even if the US is more likely than Japan to end up in a class war as a result.
All of this is inmaterial to Bitcoin, which isn't deflationary, and cannot be deflationary until well beyond any of our predictable life expectancies have long since passed.
Monetarily no, but price deflation is possible whenever demand outperforms supply.
True, but price deflation (and price inflation) are largely a reflection of the currency's perceptions at the time, not it's fundamentals.  Said another way, the aggregate value of a currency (within a working economy, not speculation as in the present case of Bitcoin) is, in large part, a result of the confidence of the user base of the currency's "usefulness" to themselves in the future.  Since the present and future supply of Bitcoin is a known variable, only an increase in the demand can result in price deflation of goods as priced in Bitcoin.  This also means that a greater number of people have confidence that they can spend Bitcoin in the future; which in turn means that it's impossible for the 'deflationary spiral' theory to apply to Bitcoin.  For if a 'deflationary spiral' were to occur in the Bitcoin economy (whenever that were to materialize) this would result in a drag in it's own perception of usefulness, and thus limit it's value.  It's a self limiting factor, so long as the economy at large has an alternative to the currency in question, which in this case is the local currencies that Bitcoin stands to replace.  Thus the deflationary spiral is impossible as applied to any 
alternative currency.
 Bitcoin is not just another value storage currency, it is a superior value exchange protocol. It brilliantly answers the question to which gold suffers: "but how do you spend it?"
I'm not sure that I agree with you here.  Not entirely.  Trading in Bitcoin is quite easy, but aquiring bitcoin in order to trade is not easy.  Using credit cards for online shopping is still easier, the privacy concerns notwithstanding.  I agree that there is a great potential for Bitcoin to dominate as a superior exchange currency, but that remains to be seen.  It is no more difficult for me to trade my metal for dollars and then go buy a new washing machine than it is for me to trade my dollars for BTC to buy books online.
Gold has been appreciating 50% this and roughly 20% each of the last ten years. Why has anyone invested in the stock market this past decade? Oh, that's right, some companies still innovate and make a profit.
Gold has been on a record tear for the past decade, but I wonder (without checking) if a purchase of Apple stock in 2000 would have outperformed gold oever teh same time frame.