Here is a retirement calculator that lets you do what if senarios -
FIRECalc: A different kind of retirement calculator
Also, as I recall, the 4% withdrawal rate has the actual amount adjusted for inflation every year and was thought to offer a 97% chance of not running out of money for 30 years. I am currently using 5% of the Dec 31 balance each year (no inflation adjustment) because I can change it at will, and being in my 70s, don't expect to need it to last 30 years.
As for Roth, a question was asked about the 5 year waiting period. I believe that refers t the opening date, not the most recent contribution, and rules are different after 59-1/2.
Last thought, if you already have both TIRA & Roth, hold the bond-like investments in TIRA since their growth is minimal right now and equities in Roth.