Engineered over plywood underlayment over old plank flooring: Stapling question.

This may be a silly question, but it's my first hardwood flooring project and I'm freaking about this. I have installed 1/2" plywood over an existing T/G plank floor. There are a lot of screws! (spaced according to APA guidelines) attaching the plywood underlayment to the existing planks. I'm going to glue just the tongues and groves of the 3/8" engineered hardwood (not glue the entire flooring down) and then staple. Won't the staples hit all those underlayment screws?

Also, I laid the plywood in the same direction as the existing plank subfloor: perpendicular to the joists (as suggested by APA rep). The length of the room runs parallel to the joists and the doorway is on one of the long walls. I'd like to run the new planks in the longest direction, parallel to the doorway, longest wall and joists. I've seen instructions that suggest the flooring should be laid perpendicular to the joists. Does the addition of the plywood underlayment allow me to run them parallel?

Thanks for all the courage I've already received from this forum!

 

No, you should still run it perpendicular. You may get away with running it parallel, but it's not wise to do so. One nail out of 500 might hit a screw and glance off. Its always a possibility. Generally if you followed a strict spacing schedule, you can mark the locations of the rows of screws and miss most of them that way. If you threw the screws in willy-nilly, well then there's no real good way to locate them.