给我普及一下行吗？什末情况要Roth IRA? 什末情况IRA? 我在fidelity上面拼命学习，还是几点不懂的，那位好心扫扫盲？

1。Roth IRA's salary limit, which means you have to earn $99,000/year and then you can open the Roth IRA account , is that true ?  Does that mean this account is only open to those high income people ?

2.还有他说，tax-free withdraw , what's the difference with traditional IRA then ?  does that mean I can withdraw it anytime with no penalty ?   then why it is specified that only like first time house buyer, education , etc, ? I m confused by that.

3. Roth IRA  still have to pay tax anyway,  so what's the benefit for this ?