Pollux, as many have said here, no camera makes you a better photographer. However having the right tool for the job makes a difference. The best carpenter in the world is not going to drive a nail with a wrench as well as an average carpenter can do it with a hammer.

Regarding what camera type, film type etc, you don't seem to be asking yourself the right questions. You ask if 800 asa film will be too grainy, well the proper question is will 800 asa film be too grainy for an enlargement of X, and even then the definition of too grainy is subjective.

As for "street photography" just what is that? Photos of people on the street done quickly and candidly? Photos of people on the street in a staged scene? That is you ask them to stop and sit (pose) for a photo? Or is you idea of street photography shooting what is considered "urban landscape", that is buildings, parks, stationary objects. You need to answer those questions.

If you plan on shooting candid photography of people on the street, then you are most likely going to benefit by using a camera that is quick to focus, focuses accurately, can be hand held. A MF rangefinder might be the best option there, a camera similar to a Mamiya 7II. If you plan to stop people on the street and have them pose, then you might be able to use a tripod and therefore a camera with a larger negative and even ground glass focusing could work. For a mix of both photographic types the mamiya RZ, Fuji GX680, Hasselblad, Rollei 6008i, etc would be a good general compromise. If you really like the pano format then a Fuji GX617, I own a couple of them, could work well. However for hand held, I would suggest only using the wider lenses on it, or far focus distances.