after 3pm, some of the popular/famous street foods might be closed liao.
about 3pm-5pm, if u do the street art first, can go ming xiang tai pastry shop for egg tarts and dim sum and drinks. its right in the area of the street arts.
http://mingxiangtai.com.my/
I suggested new lane, gurney drive kind of food cos I assume you will be sick of restaurant kind of food from the ship.
But if you want a proper sit down place, you can try Kapitan resturant. very good indian food, naans and tandoori stuff. they also got claypot briyani. there's a branch quite close to the cruise pier.
else, you can consider red garden which is right beside cheong fatt tze mansion. food wise still the same penang hawker fare though but its a beer garden and you get some thai singers and entertainer (not sure what time it starts though)
https://www.facebook.com/redgardenpenang/
for nyonya restaurant, I don't have any recommendation, nothing memorable for me