You get medals by getting a certain amount of hits in each level. The amounts are: Corneria: 150 Meteo: 200 Fortuna: 50 Sector x: 150 Titainia: 150 Blouse: 150 Venom: 200 Katina: 150 Solar: 100...
To get glasses in Star Fox 64, the Nintendo 64 game, you have to do the hard rought, which is Cornaria, Sector Y, Aquis, Zoness, Sector Z, Area 6, and Venom, and then Fox McCloud will have glasses.
It is not possible to "save" during the middle of a session and continue later on. This is because of the games Arcade style of play - you play through all 10 levels trying to rank in the high score...