Pedesign is good to help manage them but not necessary. You can add words etc and make small changes. More if you get predesign 7? I don't know if they have 8 out yet or not. ( I have 7)
Most machines have USB ports now so either a USB or a cord to your computer can be used. Depending on your set up.
There is a number of places to get free and or inexpensive designs. My favorite being www.emblibrary.com