Since Roth IRAs were first available in 1998, the oldest your Roth IRA could be is 22 years. Nonetheless, if your first legal Roth contribution was prior to 2016, your Roth is now fully qualified and tax free.
1) No tax or penalty since the distribution is qualified. You do not need to report it on Form 8606, just directly on line 4a of Form 1040.
4) Not for the distribution, but you will for the conversion on your 2019 return.
5) Line 4a only, nothing on 4b.
Hopefully, you do not have to take a large Roth distribution, since leaving the Roth balance alone will continue to generate non reportable tax free earnings for life.