Sorry if this is in the wrong category. If you are dispensed of the Sunday obligation, are you still supposed to observe Sunday as a day of rest?
The obligation to attend Mass on Sunday and HDOs is lifted. Sunday is still Sunday:
2185 On Sundays and other holy days of obligation, the faithful are to refrain from engaging in work or activities that hinder the worship owed to God, the joy proper to the Lord’s Day, the performance of the works of mercy, and the appropriate relaxation of mind and body. Family needs or important social service can legitimately excuse from the obligation of Sunday rest. The faithful should see to it that legitimate excuses do not lead to habits prejudicial to religion, family life, and health.
The charity of truth seeks holy leisure - the necessity of charity accepts just work.
Yes. Strictly speaking they are two separate, but related, obligations. Mass attendance is a way to ensure that the faithful attend to their duty to the worship due God.
Attending mass on Sundays and Holy Days is an obligation of the Church (ecclesiastic law), but the weekly rest is divine law. The Church can only dispense from ecclesiastic law, but cannot dispense divine law.