IRA and ROTH withdrawl

Hi,

Let's say I have $300,000 in rollover IRA and I retired today.

1. Convert $50K into ROTH.   Pay ordinary income tax on $50K
   1. This $50K can pass down to my heir (tax-free), correct?
2. Remaining $250K, I have to meet the annual minimum RMD withdrawal
   1. My heirs can take over the remaining balance after my past.
   2. Do they require to keep withdrawing annual RMD as well?
   3. Heirs must withdraw all remaining IRA balance by 10 years mark after my past?   They need to pay "ordinary income tax" within their tax bracket?
3. How can I apply to a part of lifetime gift exclusion with the IRA?
4. Is lifetime gift exclusion subject to tax?  If yes, how so?

Thank you !!