Centrifugal force is reactionary force of centripetal force.
4A charge particle can't move in straight line in the region where magnetic field and electric field are mutually perpendicular.
1for 2nd one, F = qxE +q(vxB)...direction of magnetic field and electric field maybe such that they might balance each other....so the charged particle can move in a straight line depending on the direction and intensity of the two fields
1for 1st one,
centrifugal force and centripetal force dont exist together.
centrifugal force is a pseudo force in non inertial frame of reference,it is not a reaction to centripetal force.
for 2nd one,
if a charged particle enters a region of magnetic and electric field with velocity=E/B where E and B are the magnitudes of electric and magnetic fields respectively,then it keeps moving undeflected in its path as the 2 forces cancel out(remember the expt of measuring e/m of an electron[1][1][1])
1and the 1st one is rightly explained by arka....centrifugal is a pseudo force which is not a reaction force for the centripetal force