vs .net and .com i dont think it has much value i think even the us companies prefer .com/.net/.org compared to .us
Compared to .com and .net,maybe most people still like to choose these two but not .us. However it doesn't mean .us have no market money. Maybe you can find its potential value after a deep research on it. Of course some promotion is absolutely necessary.
I see a big forum outsite of US using .us extension .. and this is greatly success community forum .. so its up to you to optimize the use of .us domain.
Actually not even the COMs are valuable unless you have/find a good name or a well developed website regardless the name.
Well offcourse but say a keyword domain if i have laptops.com and laptops.us the .com will have more value