Is there a maximum withdrawal for an IRA?

No, You are not required to withdraw any money from an IRA until you are 70 1/2 (RMD)- this doesn't apply to the Roth. The RMD is cal, of the amount of money you have in all your non-Roth account dividend by an age factor depend on who and how old your bene of the acoutn is. See pub 590 for the 3 different RMD charts.

No, there is no maximum. You can take it all out after 70 1/2, but if you're prior to that age I say check with the IRS, especially for penalties.