ursulines skatepark has just kids, much better: go to trone. it's just a hangout spot where you skate flatground and drink beer but totally worth it. sessions go down almost every day, but you'll most certainly meet people un the late afternoon or evening.
take the metro to trone, the spot is in front of the ING building
when you need a skateshop go to ride all day
have fries at masion antoine and avoid the touristic food street in the centre.
ixelles is nice we stayed in etterbeek right next to it.
enjoy the tripel karmeliter.