The must sees are Ruins of St. Pauls, Senado Square, Venetian Macau, Fisherman's Wharf and A-Ma Temple. You can go and check China Tour Packages(https://www.travelchinaguide.com/tour/default.htm) , there are side tours from Hong Kong to Macau, there are suggested itineraries and attractions. For the mode of travelling, there are many free shuttle buses of Casinos in Macau, you can make use of it , also you can take citybus to travel, most of the buses in Macau charges around MOP4-5 per trip per person.