You'll never starve in this town, even if you're flat broke...which is good, because short term work is really hit or miss out here, especially as it's heading into winter and there are less weekend outdoor fairs and such. But, yeah, there are a bunch of places that will feed you for free if you're willing to show up when they have the food out so hunger isn't something you need to worry about.
Otherwise, there are usually a shit ton of kids in the Haight and the vibes are usually pretty chill, if you have an instrument you can probably do decently for yourself if you play in the touristy areas, if you need a bike there's a place called Bike Kitchen that'll let you trade volunteer hours for parts and help building yourself a bike...it's a good place to chill for a bit. And feel free to message me when ya get here or if ya have specific questions...I'm rubber tramping it and plan to winter here, unless a better option presents itself, so happy to answer what questions I can.