The F&F flier has some early season southbound Alaska sailings which have base fares less than the taxes.
13032574_Travel_Agent_Friends_Family_Rates.pdf (rccl.com)
Welcome to CC.
The on-board accounts are in USD. While they might be able to refund in something other than USD (unlikely) it would be at a very bad exchange rate. Use a cash account but don't deposit anything, so you won't have to worry about a refund.
No, other a few O class itineraries, unlikely any RCI itineraries past April of 2026 will come out before Nov. Look for the 2026-27 deployment thread later this summer.
The perks could change at any time between purchase and the sailing. Implementation could also vary between ships. It could also be that the website needs an update to catch up with reality.