CrossDOS already comes with every version of AmigaOS starting with 3.1 so all you need to do to read PC formatted disks on your Amigas is to double click the PC0 icon in 'Storage/DOSDrivers' folder of the partition you booted from and then insert the disk into the disk drive. Simply copy the necessary files to the disk on the PC beforehand, including the tools you need to extract the files, which you should be able to find on Aminet. Try searching for 'DMS' or 'Disk Masher' on that site.
The A1200 will most probably have a Double Density (DD) disk drive so remember to use 720KB formatted disks on the PC. The A4000 will most likely have a High Density (HD) drive so any standard 1.44MB PC formatted disk should be fine.
Let us know if you have any issues copying the files to disk.
