How to go to the ruins of st.paul, senado square & the venetian from macau maritime ferry terminal?

As most of the ferries arrival in there are in the Outer Harbour Ferry Terminal (there are two ferry terminals in Macao), so I would just tell you the transportation from the Outer Harbour to the places you mentioned.
1. To Senado Square & Ruins of St. Paul: you can take bus no. 3 from the ferry terminal to Avenida de Almeida Ribeiro, and then walk to the southeast for about 80 yards to Senado Square. After then, you can just walk northwards to reach the Ruins of St. Paul.
2. To Venetian: walk back to Senado Square, and then walk to the southeast to Hotel Sintra, there you can take the free shuttle to Hard Rock Hotel. Venetian is located in the opposite of Hard Rock. After arrival, you will find it easily.
Both the Senado Square and Ruins of St. Paul are for free.