Hmm...I don't salt pico because it draws out water and creates a soup in the bottom. However sea salt is nice as a finishing salt (when served).
This is the method I was taught.Hmm...
I salt and let it sit on a strainer. But maybe with good fresh tomatoes that's not quite as necessary. Been relying too much on store-bought "hothouse" tomatoes recently.
As for onions, I prefer red.