For as far as I know, Samsung does not sync the fingerprint scanner to the motherboard, which means it can safely be swapped without losing functionality. Good luck with the replacement!
I do not think you’ll be able to replace it by yourself, as it is soldered directly onto the motherboard. Look for a shop that can do microsoldering. They might be able to fix it for you.
If you still have your old screen, installing it on your iPhone together with the front cam flex. Home button doesn’t have to be transfered for the phone to function. If it does work, you’ll know that the problem was the missing film. If not, your front camera flex might’ve been damaged while removing it. The sensor is not attached very tightly so it can break off of the cable quite easily.
Check if it’s bent. If it is, your motherboard might be damaged. This isn’t something that you can fix yourself. If it is not bent though, check for water damage. The iPhone 6 and 6+ are not sealed, so they are not waterproof.
See if there’s a way to calibrate the props or motors. Maybe there’s a crack in one of the propellors and it just slightly influences the way it flies.
Seems you have a new version of the controller, made for release with the PS3 Slim. Try looking for those parts. I couldn’t find anything quickly, but you can always try it yourself.
Sounds like a hardware problem. I think it’s water damage. I would not advice repairing the device yourself. Whether the water has only damaged the camera or more is impossible to tell without opening the phone, and if more has been damaged it could be unrepairable. I would advice making a full backup of your phone and see if a repair shop nearby is willing to repair it, whether it is by going there yourself or sending them an email. Always be careful when repairing water damage, as it can always cause more problems than what you can see.
Does it still charge? If it does, it might be an issue with the battery. If it doesn't, use a wooden toothpick to carefully clean out the charging port and check again. Might fix the issue.