>>3831572CUL = Close up lens, It's basically a filter you screw onto the front of your lens which lets you focus really close.
>Do you think the speed grip is worth it100% I'd highly recommend the grip it greatly improves the overall ergonomics making the camera feel like a large 35mm SLR. I never take mine off even when shooting on a tripod.
>pic related>btw do you know where I can get a different magnification glass for my prismKamerastore has a few diopters but not sure if they have the correct one you're after, just gotta look around online for one I'm afraid.
https://kamerastore.com/products/zenza-bronica-gs-6x7/Also if you need a new ground glass don't bother buying new old stock get one from Rick Oleson they're a lot cheaper. You can choose from either a microprism or a microprism with a split image in the centre like a normal 35mm SLR has, can also get custom grids etc.
https://rickoleson-brightscreen.comAnd here's the GS-1 Brochure
http://ianbfoto.com/downloads/Brochures/Bronica%20GS-1%20Brochure.pdf 