Irish citizen & US tax resident: Investment Options

[jazzforchrist]

Hi,

I'm an Irish citizen, currently on a H1B visa, and going through the Green Card process. I have no immediate plans to leave the US, but it's highly likely I'll return to Europe at some point in the next 5-10 years. I've been putting off investing savings given the apparent complexities of investment accounts for expats but feel like figuring out the complexity > being out of the market.

With that, I have a couple of Q's:

1. I'm considered a resident for tax purposes; is that sufficient to open a brokerage account in the US?
2. Are there any recommended brokers for people in my position (US resident, likely a future GC holder, but will eventually move outside of the US)?
3. I've read that some brokers will require accounts to be closed if one no longer has a US address; is that the case for all? Ideally I'd be able to keep my investments with the same broker once I leave, but have no idea if that's possible.

Thanks and appreciate the help