are there seats in the ga floor, or is it standing floor only? If its a famous artist.

Depends on the artist, but if your ticket doesnt have any number, you can bet it's just standing.

GA is usually standing, but it depends on the artist.

I've gone to 2 concerts here where I was GA and it's only been standing room (G-Eazy and Kacey Musgraves) but it depends on the artist. My guess would be yours is standing room only.