Pedal clearance can be determined simply by considering the pedal design. As far as swapping pedals goes, the pedal spindles screw directly into the crank arms. The thread is wide and torque is relatively low. If removing and reinstalling these were a problem, it would be an issue for virtually every part on the bike. Neither of these questions require bike knowledge to solve.

If the OP is looking at DA pedals, it is because he wants DA, not 105. You don't stick those on a fixie for tooling around for performance reasons.