Mandy, As a repair shop owner I would only use this inferior screen if the customer were fully aware of the differences between the two screens, accepted that the phone wouldn't perform as well as it originally did and were willing to pay for a lesser quality replacement.
The iPhone 6 has three mics on it. In order to test each of them you must take a video with the back camera using the stock camera app to test the one on the back. Ask Siri a question and see if she hears you for the second mic. Then make a phone call talking on the handset to Test the third. If all three mics work in those scenarios then it most likely isn't a hardware issue. For the earpiece speaker, record a voice memo and play it back. Make sure when you begin play back, you hit the speaker icon in the top right corner to make it turn blue and see if you can hear the recording. If that works as well then there is a 99% chance it is a software issue. Try resetting your settings first. If that doesn't work, do a backup and then reset the phone. If that doesn't work, do a restore with iTunes.
More importantly, think very hard before you try this repair yourself. The screen has to be removed from the frame before you can get to the mother board. If you've never done this repair before, there is a 99% chance your screen is going to break. That is a very expensive screen....wholesale pricing for the note 4 screen is in the range of $150.00 for the OEM part. You should consider taking it to a professional.
On an iPhone 5, the IMEI is on the back of the phone at the bottom, or you can hit the "I" icon in the lower right corner of the screen. If the IMEI begins with 990, then it is Sprint in the USA, as the Verizon variant would take any sim. If it begins with a zero, then its AT&T or T-Mobile. After narrowing down the carrier just go to one of those stores and ask them to put a sim in it to check.
Well if you did a complete restore, that would indicate that the problem isn't software. The next time it freezes on you, instead of resetting it, place your right hand on the top of your phone and your left on the bottom. With the screen facing upward, gently twist your right hand clock wise and your left counter clock wise, no more than 3 millimeters in either direction. Remember I said GENTLY. If the screen starts working after that gentle twist, you have touch disease and it is definitely hardware. Either find a shop that repairs that problem in your area, or take it to Apple.