にかかわらず and を問わず: the same result despite different conditions
Compare expressions that do not make weather, experience, or age a condition of an outcome. Distinguish not asking a question from not using a category to restrict eligibility.
Differences do not affect the result
天候にかかわらず、説明会を開きます。 means that the information session will take place regardless of the weather. It holds across weather conditions, but does not remove every other condition concerning the location or time.
参加するかどうかにかかわらず、返信してください。 requests a reply whether or not the person will participate. A nonparticipant must reply too, so separate the embedded question from the requested action.
を問わず does not use a category as a restriction
この講座は年齢を問わず参加できます。 says that the course is open regardless of age. Its main point is not using age as an eligibility restriction, rather than simply not asking an age question.
経験の有無を問わず応募できます。 says that applications are welcome with or without experience. People without experience are included, but being able to apply does not guarantee being selected.
Overlapping scope and remaining conditions
年齢にかかわらず and 年齢を問わず can overlap in notices that do not restrict people by age. Learn を問わず with category nouns such as 年齢, 国籍, and 経験の有無 to make the meaning clear.
An event described as 年齢を問わず参加できます。 may still require advance reservations. The sentence excludes age as a restriction, not necessarily fees, capacity limits, or booking requirements.
Quick check: Does 結果にかかわらず、連絡します。 mean contact will be made only after a good result?
Show the answer and why
No. It promises contact whatever the result. A difference between a good and bad result is not made a condition of contact.