No problem…Greenbelt station is right off the Beltway by the intersection of the Beltway and Route 50.

You can either drive to Greenbelt and take the MARC or Metrorail. If you do that, you might as well take the Metrorail so you can go straight to the National Mall station. If you prefer to take the MARC from Odenton, you might as well take it all the way to Union Station and then either switch to the Metrorail for National Mall or any of the other means available (walk, scooter, Uber, taxi, etc).

Yes

Actual name is “Smithsonian National Mall”station

You can also just get on the Metrorail at Greenbelt and go straight to the station nearest the Washington Monument

No

You could absolutely do that…short trip.

Yes, the MARC train is considered Light Rail…the Metrorail intersects at Union Station so you can switch there and take it wherever you want. Union Station is a perfect location to board your buses, get an Uber, taxis, etc. so you’ll have many options available to you. You can also walk to the Capitol from there which is basically the top end of the National Mall and work your way down by foot if you’d like. There’s also rental scooters and bikes everywhere.

No I mean park your car at the Metro and take the Metrorail or light rail (some stations only) in …Ubers sit in the same traffic and DC traffic sucks.

At the Metro station and ride the train in!