Sift the flour, and THEN
measure it! (If you're wondering why, try measuring it first, sifting it, and then measuring again.)
Cake freezes well.
If you are spreading the frosting on thick, you may want to refrigerate the cake after you apply the frosting between each layer until the frosting has firmed just a bit; about 10-15 minutes for each layer. (If you are frosting it thin, you probably won't need to do this.)