737 windscreens are a real pane in the preverbial. The actual windscreen is a doddle being the same as a 707 but to get to it does require starting just fwd of the seats and dismantaling towards the radome.. .You can't have the same problem as was experienced by the 1-11 skipper who took evasive action when the steward got too friendly as it is fitted from inside the frame. (Gets pushed into frame the more you pressurise.) It also has lose nuts so they can be replaced with fresh ones. . .As for time taken. Anything up to 8 hours depending on sealant. By the way the speed tape is there to stop the "not fully cured" sealant from being blown over the new screen and is removed 24 hours later.. .Most other a/c have screens fitted from the outside and need greater care that the correct bolts and torque figures are used. It does mean they can be changed much quicker.. .Delam is allowed provided it doesn't cause the heating to fail and does not impair vision. Without the manual to hand I seem to remember 2 inches max but that could be DC10.