There is an immense amount of discussion in this forum regarding your points, so you'd need to focus on specifics in order to avoid repeating what others have said. Also, money supply inflates, so Bitcoin is "constantly" deflationary only if you assume a steeper adoption pattern, which is an unknown.
(1) Prices are always changing. We are talking about a massive adoption scenario, so in usual circumstances, prices shouldn't change faster than fiat currencies or even gold. Also, inflation or deflation doesn't matter in this case, so it's more a matter of volatility than deflation/inflation.
(2) Bitcoin's value will not increase 1 million-fold in just a year, or even a decade, so there is enough time for you to decide on a different unit. Use uBTC.
There is nothing to be done practically about matters that are unknown. These issues are pretty minor if you think about the timescale they are relevant. Instead of trying to predict the future, adopting a pattern that is easier to conceptualize was a better choice.
Gold does not have a fixed supply. Over 2,000 tonnes are mined every year, increasing the supply by at least 1% annually if not more.
So is it linear? We don't know. Have we reached peak gold? Will we discover a new way to mine it? These are all unknowns. There is definitely a fixed amount of gold we can mine within a practical timescale though. What we know, is that gold is a preferred medium for storing value because it is scarce and this will not change. It would the perfect medium if supply wasn't increasing.
We don't know the future of Bitcoin either. It would be undesirable to have a generation function that would get in a feedback loop with the price, even if it were possible. So the only option is to derive a function from the desired traits of the currency.
Yes, I repeat stuff sometimes. That is because I forget I posted it before, so I post it again. You search on my posts and you are like, "Hey he posted that stupid story 3 times in the last 4 years." Of course, this is not necessarily bad, because let's face it, the average person is pretty stupid and you need to repeat stuff a lot before it sinks in.
Price stability is not a non-issue, it is a central goal of any monetary system. Gold achieves that goal because as it becomes more valuable, people work harder to extract it. For this reason gold has maintained a relatively stable value over the last 2,000. Believe or not the price of a goat, 2 gold dinars (or something like that, I forget exactly what it is), has remained pretty much the same as what it was in Mohammed's time (500AD).
For BC this will NOT be the case because there is an absolute limit to the supply. So, the policies of the existing BC client break one of the fundamental goals of a monetary system.
Also, although you can certainly start quoting things in micro Bitcoins or whatever, if you have any experience with accounting or invoicing systems you know this sort of thing is highly annoying and undesirable. Just waving your hands and saying a bunch of developers will solve this problem is something only a person inexperienced in these matters would say. If you have worked with real currencies and real retail systems you know the practicality of the denominational system is very important and has a significant impact on the willingness of people to use a currency.