Yes, they are.

I assume you mean 360 AiO cooling. According to the instructions, 280 is the maximum both at the front and at the top. https://support.fractal-design.com/support/solutions/articles/4000184344

TG simply stands for tempered glass, so you simply have a glass cover on the left-hand side.

Yes, but you have to mount it on the front panel. It's the only space available for 280 mm radiators.