re: What type of grass do I have and what Chemicals do I need?

Centipede and St Aug are sensitive to 2,4-D. If you don't calibrate your sprayer and mix correctly, you can hurt your lawn. Bermuda is a narrow leaf grass, it doesn't even know when 2,4-D hits it. Atrazine is the #1 used chemical in the world (no lie). It is slow acting, but effective.

You can use 2,4-D product on your lawn, just be precise in application