I got my Bachelor's in Chemical Engineering this June in the US and had been trying to get a job until now, but that has proven to be pretty much impossible as a non US citizen. As a result, I am now considering grad school. I have some questions I desperately hope y'all could help me out with!

This is the absolute worst justification for pursuing a research-based graduate degree, and I could not recommend pursuing one unless you really know what you'd be getting into. To my recollection, PhD programs have a 50% retention rate, and no mention of research experience in your post is worrying. I'd be concerned that you'd open yourself up to a world of depression, self doubt, employee-employer power imbalance, and financial insecurity, which are common among even the most well-prepared and calculated graduate students. I cannot speak to the benefits of MS programs in ChemE. ​