I'll be checking in Holiday Inn along Rua Macau. How can I maximize the free casino shuttle buses?

You can take the free shuttle bus of Hard Rock Hotel to visitTaipa Village, Venetian and Ruins of St. Paul's. The Senado Square is only 500 meters from Ruins of St. Paul's, so you can walk there after visiting Ruins of St. Paul's.
As for Fisherman's Wharf, you may need to take the free shuttle bus of Hard Rock Hotel to HK-Macau Port where you can transfer another free shuttle bus to visit Fisherman's Wharf.
These buses all start from the entrance pass of the city.