Forward Exchange rate: Interest rate and dates conventions

I’ve been looking into the FX forward rates. While doing the excercises, I’ve noticied that sometimes they use compound return, sometimes simple interest, sometimes annualized. If you look at the economics section where the same subject was considered, they were always using simple annualized interest. Why this difference?

Another point is the date convention. Derivatives section uses 365 days, but only 360 is considred within the economics.