Thoughts on the hoopla..

Water wasn't an absurd request, it just wasn't properly initiated. Push the button that looks like a stick figure holding a tray and a FA will appear shortly and take your request. Even WN has given me a can of water prior to take-off when i said i wanted to take a pill after I pushed the button.

Now a few notes on cultural differences - ASL to people who are unfamiliar looks very aggressive. It's the same sort of way that people who speak English think people who speak German appear to be constantly shouting or angry. The movements are sharp and verbose and come off as aggressive gestures. Thus if you're gesturing to a FA in the galley of an aircraft they likely felt very intimidated. It explains why you were sent back to your seat. You're not supposed to be there and very likely scared her.

Also, planes are generally a very quiet environment - it has been my experience that often people who are deaf do not realize how much noise they are making from movement and it can sometimes offend/annoy others.

Pad and paper are something I had to do daily checks for in my customer service position to assure we had the materials should the need arise. I think it is something the airline should have, but I can understand if they are not prepared (not every company is forward thinking.)