Is "walking by the street" grammatical? Or do I need to write "in/on the street"? Do they convey a different meaning?
Walking by the street could either mean "walking near the street" as in "I'm walking by the street, on the sidewalk" or "walking past the street" as in "I meant to turn onto Main Street, but I walked by it instead".
Either way, walking near the street or walking past the street are not the same thing as walking in the street, so yes, they do convey a different meaning.
Edit- You guys win. Past it is.
In the Corpus of Contemporary American English (COCA), a search for "walking * the street" finds prepositions used with the following frequencies:
down, 509 times; along, 36; on, 33; across, 25; in, 25; up, 20; around, 5; into, 3; to, 2; toward, 1; through, 1; off, 1; by, 1.
I repeated the same search with walking replaced by each of the tenses of walk, run, come, and go, and added up the frequencies of the prepositions. The results were down, 1,359 times; across, 349; up, 152; into, 84; along, 81; on, 80; in, 74; to, 60; from, 29; off, 24; around, 14; toward, 9; through, 7; by, 4; onto, 3; towards, 3; over, 2; under, 2; after, 1; alongside, 1; beneath, 1; unto, 1. Of course, the choice of preposition depends on the meaning you want to convey. To describe someone traveling along a street, the preferred prepositions are down, up, and along.
The one quote that uses "walking by" is "When you're here and you listen to people walking by the street, saying, 'Look at this, look at that,' you know, you did it." The quote seems to come from a transcription of an interview with someone who works on maintaining the appearance of signs. The three other uses of by are all "goes/going by the street name"; they have nothing to do with an actual street.
To me, "walking by the street" sounds as if it might mean "coming by way of the street," but I wouldn't use the phrase "walking by the street" to convey that meaning.