Bitcoin proponents tend to have a vested interest and can be.. less than objective.
@1: A trade alone does not help BTC stabilise. We ARE seeing an increase in BTC trade, but all of this is pegged to local currency, and usually traded out for that immediately. As it is held for a very short period, there is no real effect on price, and is essentially the same as cashing out.[1] What might help BTC stabilise would be if there were a true, significant BTC economy, that is, items priced in BTC, rather than pegged to local currency. When I wake up tomorrow I can reasonably expect my loaf of bread is going to cost the same as it did when I went to bed. But that can't happen (yet) with BTC, because pegging goods to BTC carries far too much risk due to the volatility. Frankly, I can't see an attractive way to get to a situation where there is a substantial, viable BTC-first economy-- displacing local currencies as the first-choice isn't going to be easy. The only thing affecting the price of BTC is people buying and continuing to hold BTC (ie, in the absence of a real BTC economy-- speculators).
Further, I’m sure you can paint BTC stability as improving/worsening based simply on altering the time frame involved. The fact is the volatility is way too high (for consistent pricing), and we certainly don't have enough evidence to predict the future. You might have thought it was stabilising in October of last year before all hell broke loose.
@2: Not really a coherent argument there. An upward price trend (existing for whatever reason) encourages hoarding, which reduces liquidity. This creates a feedback loop, resulting in bubbles and crashes. Deflationary + speculation inherently leads to this, and we've seen it over and over already with BTC. Again, there is a chicken/egg problem because only speculators are interested in it, making it volatile, making it no good for non-speculators, which keeps it volatile! I think the best we could hope for is a little worse than gold (as it continues to be mined), which AFAIK still carries a significant amount of instability.
All this is not to say that bitcoin can't, or won't, be a long term success. It may well be; it has first-mover advantage, there is significant vested interest in it succeeding from those who have bought in, and it has a vast computing army. But it could be displaced. Or marginalised by an unlimited number of clones.
1. Ironically it is in a way simply passing half the transaction cost onto the customer.