The US is very large and diverse, but here are some general rules of thumb:
1) The US Gov doesn't protect much against extreme cases - that's why health insurance (generally through an employer) is important.
2) America is a very, very hard place to be poor.
3) Living like you see on TV (in NYC, LA, SF, etc, or in a cool downtown loft in an urban neighborhood) is insanely expensive and it's only possible if you design your career and life around it.
4) By trading commute time, "coolness"/novelty of neighborhood, and/or school district, and metro area, you can live well on a very reasonable middle class income. Living in Chicago, Charlotte, Minneapolis, Indianapolis, Pittsburgh, any big city in Texas or Ohio, avoids the super high cost of coastal cities.
IANAL, but as far as getting into the US, if you can have an employer sponsor you, I believe it's much easier than applying on your own. This ... may not be the easiest time to get into the USA.