It will apply to both before take off and landing. You arm the spoilers the same way for both scenarios. And yes, the only problem with this mapping is that you can’t apply 1/2 deploy. Only either full retract or full deploy. It’s an acceptable tradeoff I believe.
The gear up and down is meant to be double bound to the same button. That’s just how it is in the default binding. But you can’t just double bind them the same way. It has to use the default TCA Quadrant profile. And you change everything else to match except for the landing gear. As long as you leave it alone to the default double binding. The landing gear should work fine.