Issue: USC filing US Bankruptcy as P.R. in Canada

[usc-in-canada]

I'm a US Citizen living as a PR in Canada for last few years (family sponsorship). I kept pace with the payments on my massive US credit card debt... until earlier this year. It is looking like filing BK might be my only option.

Profile: All my debts are US Credit cards (fallout from a remodel / resale of our former US primary residence that lost 35% of its value). I have no assets in either place except for one: my very old self-directed IRA owns a small percentage of a FourPlex, which is almost impossible to sell. I own no property. I’m self employed, get paid by US sources in US dollars. We live a simple no asset, no retirement, debt-free life here in Canada. I report all income, file Cdn taxes, then US each year.

These are my questions:

1- can I file BK in any US state, like the closest state for me to drive to? Or do I have to file in the state I last lived in or owned property in?
2- is it best (or required) to update all the creditors that I live in Canada now? Or keep using the paperless US PMB that scans mail to me by email?. I prefer the US PMB as its paperless and more reliable, because US firms notoriously goof up Canadian postal addresses.
3- Will a US BK affect my Canadian credit, like eventual ability to qualify for car or house? We don’t use much here at the moment, just have 2 new cards, with zero balances.
4- any other cross border issues I need to be tracking?