Clairol Professional Shimmer Lights Permanent Cream Toner for Cool Blonde Hair Results with Less Breakage* and Shiny Hair

How long will this last? Is it a demi color?

Which one of these 3 toners has a blue base?

Should developer be used with this?

If i’m using the full 2oz tube of toner, i’ll need 4oz of developer, correct? which would mean i need to buy two bottles of the 3.6oz developer?