Is this light bar waterproof? I want to mount it on my headache rack.

Thank you for your question !  Yes,it is.

Do you ship internationally (Ireland or UK)

Hello, sure, we ship to Ireland or UK for free.

Does this light bar come with rubber suckers

Hello, thank you for your question! Yes, this light bar come with rubber suckers, it's easy installation.

Is this able to suction on your back window? I have a 2000 Chevy Silverado and I want to suction it to my back window and use it to direct traffic or just as a flashing light bar.

Hello, yes, it's very easy installation with rubber suckers.

Does it come with wiring harness aswell? Some companies do not give them to you they are a separate purchase.

Yes, the flash light will come with the wiring harness.