Re: Go by foot.
NOT A TEACHER
I will only add that saying "go by foot" is a common mistake among learners of English. The reason is that the learners think that if you, for example, can say "go somewhere by car/plane/taxi etc." it means that you always state the means of transportation after "by" and thus "go by foot" is possible. Sadly for us learners, while that works with machinery, it does not work with feet. Btw. a useful alternative to "go somewhere by foot" is simply saying "walk somewhere".
I'm not a teacher, or a native English speaker. Feel free to edit my posts if you encounter any mistakes in them (be it grammatical or vocabular). It'll help me to improve my command of English.