Price stability will eventually occur once it is used by more and more individuals and organizations
No. For example: every country has a paper money/fiat, used by many people; the exchange rates is not always stable. Oil and coal are used by many people and companies; the prices are not stable. Supply and demand are still the main factors.
Its a new currency it will eventually start being considered as legal tender in a lot of countries it makes sense for the governments to capitalize on it by taxing it and profiting from its use. Legal tender allows them to officially recognize it and tax it even further. It means that we will be getting taxed more on cryptocurrencies but I think that is the price we need to pay for it to become closer to mainstream currency.
If legal tender = main currency, as long as there is a government, Bitcoin will never become main currency in a country. Bitcoin will only be an alternative payment tool. If any country allows Bitcoin to be a currency, that country will still have a primary centralized currency.