Qualification questions

[V50]

Apologies if too simple/already answered, but couldn't find an answer for this. 

1) How do I qualify the 4th placed of a cup. I've set the ranking levels up properly but can't find a way to do this. Perhaps a hidden league stage?

2) Something I've wanted to ask for years, how do you account for qualification fall-backs, for example how do you add a slot for the host team in a competition?

3) I'm making the Caribbean Championship in game, but never found a way to have a system similar to the european competitions, namely that the highest rep/rank leagues get more places than the lower ones. The whole "top/bottom" nation qualification doesn't seem to work out for me as if I say "pick Best Nation Teams", it always ends up a complete random mess, with league winners dropped for highest rep teams.

Thanks for your time.