First cost of coffee need to fixed in satoshis and everyday I pay same amount of satoshis to buy that coffee. (using $5 as example my satoshi payment differ every day).
I do not think business can work on volatile rate of bitcoin (in terms of fiat).
That may be one of those "chicken or egg" scenarios. It remains to be seen whether volatility decreases naturally as adoption begins to increase, or whether a reduction in volatility is a prerequisite for adoption to start increasing. I tend to lean more towards the former.
Indeed. It's likely that fees are a bigger psychological barrier than the volatility. That's not to say we shouldn't worry about the volatility, but I think it's reasonable to assume that once the emphasis has shifted away from Bitcoin being a purely speculative asset, the volatility will become less of an issue when people use it more like a currency.