By default, if you plug an AP225 into two POE port, it will boot up on the the first switch to provide it POE. It will not draw any power from the second port. If at any time POE is interrupted to the AP on that first port, it will reboot and come up on the second port that provides it POE. You cannot avoid the reboot.
LACP and GRE striping are not related to redundancy; they are configured when you want additional throughput. As a practical matter, due to protocol overhead and contention, there are few instances when the actual wired sustained throughput of an AP225 would approach or even exceed the single gigabit port that it is connected to.