Q.Norfolk Pine
I live in central FL and have a Norfolk Pine that got hit by frost/ice this winter. It is 30 feet + tall so covering is not a practical option (too late anyway). Now the bottom branches are turning brown and I have the ground covered with brown fronds. What should I do? I have read many of the questions and answers that look like I should wait for a couple of months and see but is there anything I can do : trim; fertilize; etc. that may give my tree a better chance to survive?

Waiting is the best option here. Fertilizing after damage can, further, make the problem worse. If you add anything, then I would suggest a plant additive called vitamin b1. It is important to get one for plants, as it is made for them, specifically. Thrive Alive makes a good product for use. I would not suggest adding anything else, as they will likely recover on their own.