is it best never to purchase songs from the itune stores. it is better to purchase a cd

I am very frustrated. I signed up for the cloud service and i not all of them downloaded. I cannot find them anymore. However my old ipod classic still has several of them. I am concerned that if i hook up my old classic ipod they will be erased. In other words it will just worsen my problem. is there a way to get the songs off my ipod classic on to my computer. I am a very dissatified apple user.