Few cons of Binance US is less pairs and liquidity as mk4 said, and afaik it also requires you to perform KYC upon sign up, that or just much more strict KYC requirements compared to the Binance outside of US (not sure since I don't really use it). If you don't have any qualms about that, I'd suppose Binance US would work with you.
I heard people who use binance.com in the US... then moved on to binance.us... which is basically almost the same thing? Its only with other us traders right? But is there a ton of volume there? And do they have the exact coins that are traded in binance.com? The thing though is i wouldn't be able to use binance.US while outside the US right? I would sign up for an account while abroad... so would there be issue with this?
It should be fine I think? You're still technically a US citizen and details you would put out would point out to you being one anyway, so I hardly doubt issues would arise. As for the altcoins, from what I've heard there's a different list between the US one, and are still currently adding more coins to it. Well, that news is around 3-4 months old, so the list may be almost complete by now.