Serenes Forest is an amazing resource for Fire Emblem fans. It's been a while since I used it but I think it's time to break it out again. Posting here because I think some people will find it useful. Breaks down the base stats and growth rates and max stats of different units, the modifiers to stats that classes add, and eventually it'll probably have a complete guide of every calculation the game does, if they do what they did for past games in the series.
Mild spoiler warning, as the lists will obviously contain characters and elements you may not have seen yet.