1. I can't remember what format the cert is actually created in - what did it say in the manual? I'm fairly certain it was PEM.
2. After you've created the key on F5-A, sent it to the CA, and imported the fullfillment, you'll now have a cert/key combo on F5-A. If you simply click on a key or cert, you'll see an option to export. You can export the key/cert in text or file format. On F5-B, you simply have to do an "import" instead and paste/upload the content you exported from F5-A. You'll have to export both the key and the cert from F5-A to F5-B