Yeah most things are open but you need to book entry for museums and galleries. As well as book most restaurants.
Baltic, discovery museum, Hatton gallery, great North museum, Side gallery are all interesting. Also Newcastle Castle. If you like old architecture grey street is quite nice too. There's also some remains of the city wall.
Tyneside cinema is nice, in a heritage (but renovated) building
For food and drink I like central for sourdough pizza, vegano, by the river Co, rehouse does nice pose and is in a tudor building! Dabawhal and or my dheli do good Indian food. Fat hippo is good for burgers. Great British cupcakery is nice for cakes in the Quayside. The granger market has started to get a few small more casual food places and the market is worth a look.
A little walk along the Quayside is nice. They've just put up some fake grass, big planters and deck chairs to make it a bit of an urban park for a place to relax for 5.
There is a boat trip either up or down the Tyne which is quite good.
I'd also say the metro to tynemouth and whiteley Bay is worth a trip. It is probably 30 min from town.