Going from a Mac Plus to an Intel iMac is quite an upgrade. I think the cheapest (read: free) and quickest method would be to use something like Mini vMac or Basilisk II. Google will help you find guides on how to set these up. There are many archives of Mac software online that have Word and MacWrite (see my signature for a link to Mac Hut, my archive of old Mac software), since USB floppy drives do not support 400/800K floppies (which I assume your version of those programs are on).