Thank you for your question and we are sorry to hear you are experiencing an issue with your caps. The Florida sun alone should not cause the caps to warp, but it is possible that concentrated reflected heat from low-E windows, etc. that may be the cause. We ask that you file a warranty claim at https://fiberon.insightpro.com/#/page/customer-warranty-request so we may address your concerns.
Thank you for your question. The caps have a true 5 inch opening, so they will be loose on your post.
Thank you for your question. The caps will slide on to the post sleeve, but can be secured using silicon or a quality exterior adhesive to be held permanently in place.