You can get bus times at www.sbb.ch. Just enter Savosa, Posta and Lugano, Stazione Nord. The journey takes 7 minutes. The bus terminates at Lugano, Autosilo Balestra but this is not quite so convenient for the city centre. You can catch the funicular down to the centre from the station. However as the last bus leaves Lugano, Stazione Nord at 1909 you will either have to walk back or use your car!
As mube says there are plenty of restaurants in the centre. Just walk round, take a look at the menus and make a choice. You will be able to sit outside many of them in August. If you use the following link you will see just how many there are! Just zoom in to get a better idea. There is a small car park in front of Ristorante Mary (just below the red ring when you zoom right in).
map.search.ch/lugano/piazza-riforma…
If you are looking to eat on a budget then try the restaurant in the Manor Store, which is open until 2200 every evening.
www.manor.ch/fr/storeweb/index.cfm…