Brussels - Easter Monday
 

Just wondering how dead is the city on Easter Monday.

I have a 6 hour transit and wanted to go into the city (I went to BRU before so sort of know my way around Grand Place etc..)

Also any recommendations to shopping, eating etc...

What times of day will you be there? What kind of food do you like? Without knowing your predilections, it's very difficult to make suggestions. Certainly you can take a train to Centraal / Central and walk two blocks to the Rue des Bouchers and its variety of restaurants, not to mention the shopping at Galeries St. Hubert (Galerie du Roi and Galerie de la Reine), and all that lies between there and the Grand Place, for example.

I will arrive by 6:30am. I just want to know will things actualy be open on Easter Monday?

I am thinking maybe some traditional Belgium food (Mussels) or maybe some Michelin Star restaurant/bistro type places.

If you arrive at 6:30 am and have a six hour layover you’ll be leaving at around 12:30. This means you’ll have to leave Brussels at 11:30 am (or sooner). You will not find any “traditional Belgium food (Mussels) or maybe some Michelin Star restaurant/bistro type places” open before that time.
The best you can hope for is a nice place to have a coffee around the "Grote Markt" (Grand Place), and maybe a small snack. Those places should be open even on Easter Monday morning.
Shops will generally be closed.

As of the public holiday at Easter Monday there are no shops opened. You should take the train from the Airport to Brussels City. At the airport there is nothing special to see. You could also explore the surrounding areas like Zaventem.