The Vivitar 252 is also a dandy compact auto flash for this camera. It's PC cord is stowed in the base of the flash, and has two auto levels. It also has an AC connector, for use inside. I paid about $10 on eBay for mine, in box with case, manual and AC cord. It'll "look right" on your GS (I have a GSN).
I believe the 251 is also an auto flash, and also the 253, though I'm not so familiar with these.
For a hood, I have a Hoya metal hood that stays on mine all the time, that will accept a 58mm Yashica snap-cap. Might be a little tight in the corners to put on top of a filter, but I haven't tried that, yet. Very handy, not too much viewfinder interference and helps me keep my dumb fingerprints off the glass.