Hello,
on the issue of no input port get a $150.00 USB 3 Focusrite Audio Interface such as the Scarlett 2i2. It has Opamps not tubes but it's small and compact and sounds a whole lot better than what the audio-in used to sound like. Plus, you can plug in a mic or quarter inch cable which means you don't need an xlr to quarter inch a sony sony like you would have to do with the older model.
If you got a Retna you got the best deal because the other model has the audio in but it doesn't have the flash hard drive on the chip with no moving parts. It's much faster if you need to process large amouts of data such as using an audio DAW. The downside is replacing the drive.
The thunderbolt ports are great because you can convert your other drive to an external if it's large enough to do you any good. I converted one from an internal I replaced in a very old Macbook Pro. It's a USB 3. if you need to use a firewire and it's a 400 then that might be a problem.
If you need to use a express card go with Sonett Technologies but get the pro.
Congradulations to everyone who got the Retina.
Best,
Alan Warrick