Hi and thanks for your question. You definitely don't need to forward the ports on your router unless your iPad is connected to another subnet/router entirely. You also don't need to add your iPad manually. The Bonjour stuff should work straight out of the box. Do not forward any ports on your router.
First, a silly question: is the iPad and the computer connected to the same router? Can you verify that? Also, you need to start MIDI Designer (or another MIDI app) on the iPad, otherwise the computer will not see it.
Can MIDI Designer see the computer?
Check mididesigner.com/connect if you haven't already.
Looking forward to getting you connected, even if it takes a couple rounds of comments.