To the upgraded Bluetooth & Wifi Card, it's actually not a new upgrade, but just the latest revision of that upgrade path. Back in the day, most of us started to replace it with the last iMac module card. Since then it developed to todays spec with is actually impressive. Back than the motivation was to get / add those two features, -> Apple's Handoff and Continuity feature. That's what you get if you replace that card apart from the USB feature.
Continuity feature:
Handoff feature:
One more thing: Can you tell me what kind of Display do you use at the moment? Does your screen have a built in USB hub at the back of your screen that you connect to your MP5.1 USB? Most devices suffer from not having USB drivers, so I absolutely would upgrade it. In my case, my really great Bowers&Wilkins USB Stereo speakers did not work any more before my USB 2.0 board upgrade.
Other than that, you should be fine regarding your list, mentioned above. The only thing I would do is to get that wifi/Blutooth upgrade first and do the OCLP upgrade last. This way, everything will be set correctly on the hardware end, because OCLP will recognise the changed hardware upfront. If you do the hardware upgrade afterwards, you may need to do the post OCLP thingy one more time to get the new hardware recognised.
Hope everything will work out for you. Keep us updated how everything worked out for you.
Kind regards from the Alps, Bavaria