I can't help you with the Fireline question, having never used it. The smallest braided line that I have used on a baitcaster is 30# test, which is 8# diameter. I wouldn't go any smaller than that.
As far as PLine, I have used the PLine fluoroclear and have been very happy with it. It is a copolymer with a fluoro coating. I know that a few others on the site have used the PLine Fluorocarbon line and have liked it very much as well.
As far as PLine, I have used the PLine fluoroclear and have been very happy with it. It is a copolymer with a fluoro coating. I know that a few others on the site have used the PLine Fluorocarbon line and have liked it very much as well.