Lets tackle them one by one:
1) Is this definition true?
Not entirely. Stable coin need not be pegged only to fiat currencies. We can also peg a stable coin to exchange traded commodities like precious metals whose price remain fairly stable. You can also have stable coins linked to cryptocurrencies via smart contracts.
(2) And if yes, Is it possible to ...
Why do people prefer to buy Bitcoin over other cryptocurrencies?
There are many reasons:
Bitcoin is the most capitalized market amongst cryptocurrencies, and that is an important measure for any form of money. If it is difficult to trade a form of money without crashing the price of it, then it is not a very useful money in the first place! As ...
Indeed, USDC has a backdoor built in to allow for the freezing and/or seizure of funds if it is believed illicit activity is involved. In other words, any address can be blacklisted and funds frozen. Not very stable for a stable coin, right?