For a Mac Classic, I recommend installing both System 6.0.8 and System 7.0.1, along with System Picker to switch between the two. Both OS'es can be downloaded freely from the Apple site, so no need to look for those:
System 6
System 7.0
Since the Classic has a 1.44M SuperDrive, you can write those images to a disk using any modern floppy-equipped PC or Mac. It's probably easier to do on a Mac, because it should have all the software required to deal with MacBinary files, StuffIt archives and DiskCopy images. On a PC, I highly recommend using an emulator such as Mini vMac, along with HFVExplorer to deal with HFS disks and images. This combination allows you to 'preprocess' vintage Mac software in various ways before actually placing it on a real Mac. I can post more details about working with Mac files on a PC if you want.
As for other applications, you can find a lot of it still floating around on the 'net. For obvious reasons, I can't give you any specific links here, other than the official Apple download site. A bit of resourcefulness goes a long way, if you want to find more.
System 6
System 7.0
Since the Classic has a 1.44M SuperDrive, you can write those images to a disk using any modern floppy-equipped PC or Mac. It's probably easier to do on a Mac, because it should have all the software required to deal with MacBinary files, StuffIt archives and DiskCopy images. On a PC, I highly recommend using an emulator such as Mini vMac, along with HFVExplorer to deal with HFS disks and images. This combination allows you to 'preprocess' vintage Mac software in various ways before actually placing it on a real Mac. I can post more details about working with Mac files on a PC if you want.
As for other applications, you can find a lot of it still floating around on the 'net. For obvious reasons, I can't give you any specific links here, other than the official Apple download site. A bit of resourcefulness goes a long way, if you want to find more.