As far as the accent barrier, if you have a heavy accent, speak slightly slower (makes it easier to understand and easier to interrupt). Also if you're on a phone line or especially a speaker phone, ask if you're speaking loud enough. Your interviewer's comments about laid back SF folk is odd I think, but sometimes the language barrier can make you seem more stern and unapproachable than you actually are. Maybe learn some conversational idioms to diffuse tensions... "no worries", "I get what you're saying, but", "if I understand you correctly, then", "yeah we're in agreement there, but", "just to clarify,", "sounds good" ... stuff like that

Also, don't let it get in your head that Americans' stereotypes or past experiences with engineers are going to significantly impact you. Most people will take a fresh and honest look at you, and most everyone no matter where they're from carries some baggage with them (devs from mega corps, devs from no-name schools, devs who have been unemployed, devs from yet another failed startup, devs working in some language that's too hip or not hip enough, etc etc).

I've only ever worked on a professional agency level with two Indians and they were outsourced to, and to be honest it's mixed, they always delivered projects on time, but the code they provided was less than fantastic and reading it - and as a superset, integrating it - was a pain.

Not that this is a mark on all Indian developers, Suchi Sendrahali is someone I've worked with in the past and he was fantastic.

Thanks for sharing your experience :)