Moving to San Francisco from Ireland in a month and could use some advice/tips.

I just posted this exact thread in AskReddit but I figured I do it here as well in case some people didn't see it over there. Basically I got a year long visa to go anywhere in America, with an option to stay on longer if I have a job that I wants to keep me, and decided to choose San Francisco. I've got no job or accommodation lined up but I just need to get out of Dublin for a while and I've heard nothing but amazing things about San Fran from anyone that's been there. I love it here but I just want to do something different, plus the recession here is getting pretty depressing. So I thought I would ask reddit if they could recommend how to go about getting accommodation and a job. I definitely want to live in the city so where are the good areas with loads of fun shit to do? What is the public transport like? What should I be looking to pay? And as far as jobs go, where should I be looking online for good start-ups? Should I look to work in San Francisco or in Silicon Valley? I've got a B.A. in Economics and recently did a diploma in Online Marketing and SEO so what are my options? I'm pretty much willing to work in any industry provided they don't treat me like shit and give me some real responsibility. So if there's any San Fran redditors out there who think they can help me out, just let me know! Cheers!