May withholding exculpatory and impeaching evidence be disregarded and/or used to obtain or sustain a conviction?

Questions Presented for Review: I.) May withholding exculpatory and impeaching evidence [in violation of Brady (373 U.S. 83, '63) /Due Process as Guaranteed under the 5th and 14th Amendments to the U.S. Constitution] be disregarded and/or used to obtain or sustain a conviction? II.) May court-appointed [trial] counsel's failure to investigate (a) discovery and/or (b) the requisite authority applicable to the proceedings he was appointed to [in violation of Due Process and Effective Assistance as Guaranteed under the 5th, 6th, and 14th Amendments to the U.S. Constitution] be disregarded to sustain a conviction obtained therefrom? III.) May the misapplication of the doctrine of res judicata to a question of law /interpretation of statute requiring de novo review [in violation of Due Process and Equal Protection under the 5th and 14th Amendments to the U.S. Constitution] be disregarded to sustain a void judgment? . IV.) May a lower court's disregard of statutory requirements /authority rendering both the attempted judgment void and the doctrine of res judicata inapplicable [in violation of Due Process and Equal Protection of the law under the 5th and 14th Amendments to the U.S. Constitution] be disregarded to sustain a void judgment? : (ii-)