They would just replace the headphone jack. If you can find the parts you could do it yourself otherwise if you take it somewhere, they'll replace the part. Perfectly doable.

Yes you can. You need to find a hard drive (or in your case a solid state hard drive) that is no more than 9.5mm tall (0.37 inches) and uses a SATA II connection. That's it.

Try this, 1. Turn your device off and let it sit for about a minute (to fully turn off). 2. Hold the VOLUME UP button and hold POWER button (start with the volume button then hold both together. This will take you to a RECOVERY MENU. 3. When you see the Samsung logo you can let go, it should take you to a RECOVERY MENU. 4. Use the volume up/down buttons to navigate the menu and use the power button as ACCEPT/OK. 5. Go down and select WIPE CACHE PARTITION and hit the power button to accept. 6. It should take a few seconds to wipe your cache (none of your personal data/apps will be deleted, only system junk files). 7. When it's complete, select REBOOT SYSTEM NOW to reboot your phone and boot up normally. Hopefully this should clear the errors that are in the app. Regards, Kevin.

I'm sure the two aluminum looking pieces are the antennas that go in front of the fan unit. Check out the Antenna replacement guides to check if its the same part you are referring to.