Yes, 5.1 works via the optical connection, I connected my laptop to the 5.1 system this way. Software is included with various functions such as equalisers and room effects. The volume knob on the unit has a long delay, that's the only flaw, but you don't have to use it to adjust the volume. Otherwise, I can highly recommend it. Much better sound quality and performance than the laptop sound card and 5.1 output works, which is why I bought it.
According to the manufacturer's site, it is only compatible with Windows (fully). On a Mac, you can most likely connect it and sound will come out, but there are no drivers from Creative for Mac and the remote control cannot be used either.
PS: Mac's use MacOs and not IOS. IOS is for Apple's mobile devices.
I need the SBX-Fi 5.1 Pro as an ext. sound card on the laptop because the built-in card goes haywire. The X-Fi has a headphone connection and I can listen to films etc. with it. I am very satisfied. I don't know what you mean by headphone amplifier though.
I bought the Sound Blaster only recently. I connected my Logitech z906 5.1 system to the sound card via an optical cable and it works perfectly (great sound quality). So I can only recommend this purchase ;) You will have to buy the optical cable separately.