does that mean that (for the next transaction) this BTC address should be taken or the opposite?
-snip-
I guess "Freeze" means "Don't touch".
The freeze setting is permanent until you unfreeze it
But will only work client-side, means that if you have other instance of your wallet, your freeze selections wont apply there automatically.
"Freeze"-->Freeze Coin
and
"Freeze"-->Address
?
Shouldn't it be the same?
"Freeze Address" freezes all of the UTXO that's associated with that address.
It will apply as long as "Coin control active" message is displayed.