Pippi, that's a lot of questions in one post !!!
When salvia seeds are maturing, they're white
Don't harvest them until they're dark brown or black. Then they're ripe
Mature seeds
I harvest whole stems. By then most of the stem will be turning brown, as in the second picture. I scrunch into a bag, shake and dump into a colander to sift seeds from garbage.
Too much bold color? Wouldn't be for me. I love lots of wild color. Biggest challenge might be spacing for height x width.
Karen