1. Sam is sitting down in a chair and playing drum.
2. Sam is sitting down in a chair and playing the drum.
3. Sam is sitting down in a chair and playing a drum.
4. Sam is sitting down in a chair and playing drums.
5. Sam is sitting down in a chair and playing the drums.
(Which ones are grammatical? In a band he is performing with the others. There are two drums and another kind of percussion before him.)