I like the idea. Since I am a US citizen and the ICO is ongoing for a long while, I can wait to buy in at a latter time. No need to rush in here to EOS. It's very new and needs time to develop.
Ethereum killer? ... I doubt it. However, I think it can withstand side-by-side with ETH eventually. It has a lot of catching up to do.
I don't think they will "allow legally" a US citizen to ever buy into an ICO after recent news events, but getting EOS off an exchange will be something different.
It's already tradable on exchanges. Bitfinex and a few others list the EOS/BTC pair.
Correct, but you cannot buy directly from the site for the actual ICO, as a US citizen. Buying it off an exchange means "theoretically" someone else bought it first(from another country) then placed it on the exchange(or just used a VPN).