1) spread it out like glosso
2) I have plenty of red plants, and I'm using 390wt PC, my tank is 24in tall. Most of mine doesn't turn red until about a foot tall, then gets progressively more red as it nears the surface. What are your nitrate and Fe levels?
3) that's normal when dosing excel
When you say 'seachem' do you mean flourish or flourish excel?
"Soft" plants like cabomba, crypts, vals need to be introduced gently to excel.
I've not heard these plants to be sensitive to Flourish.
What is your method of CO2 dispersal?