Doubt Siri could hear me in a manufacturing facility where it's a bit loud. Not gonna happen. lol
Plus, don't you have to be able to touch the watch to activate Siri anyway? Kinda makes the point moot if so. I don't have my watch yet, but if it's anything like with the phone then Siri isn't all that useful anyway....she's very hard of hearing in my experience.
People have said that Siri seems to work better for them on the watch. (can't say myself as I'm still waiting). No, you don't have to touch the watch to activate Siri - you say "Hey Siri"
If I were you, I'd order one and try it out. You have 14 days (and it looks like that's business days, not calendar days) to try it out and return it if it's not for you. Apple's been very cooperative with people doing this, as it's a new category.
Oh...and on the thread topic. I think there will be many updates - at least for the first little while. This is a 1.0 product. There will be lots of bug fixes and little features coming that couldn't quite make the launch window.