Questions & Answers about Я часто хожу пешком до метро.
Хожу is the multidirectional/habitual verb: “I walk (repeatedly, generally).”
Иду is the unidirectional/in-progress verb: “I am walking (right now), in one direction.”
With часто (often), you use хожу to express a repeated habit.
До means “up to/as far as (the metro),” i.e., to the station/entrance.
В метро means “into/inside the subway.” You walk до метро; if you’re entering the system, you can say иду в метро.