Ok don't use 3u tools, dr fone etc, these are a bunch of trash apps. Only the iTunes. Please post me the error it gave.

Of course you can when you have a sync enabled macbook, or u can just leave it charged and connected to wifi. iPhone makes automatic backups( if you have not disabled in particular) when connected to wifi and charging. You can log on to other computer or macbook to retrive your icloud photos.

Yes. Apple uses pentalobe screws to hold the folder and screen which is same for all models

Oh Man! Just replace with the SDD and you are good to go.

Even though the OS is corrupted the mac will at least boot with some instructions. It is a hardware failure. Just unplug the charger and remove all the static from the board pressing the power button for 2 minutes without the power cord. Then give it a shot. if you are a technical expert, open up the MacBook and remove the battery with plastic spudger remember with plastic and press the power for 2 minutes without the cord.

Your machine having problem with heavy load. Reduce he weight/ load, so that it will procees.

Oh Man! You messed up with your front earpiece flex cable. The flex cable should connect to the board which is responsible to get power to earpiece.

Ok you gone a long way! First remove the battery carefully with PLASTIC SPUDGER or else u might short the battery terminals with metal one. Now power on the device without battery for at least 1 min to remove any static. Check for any damage created accidentally when removing the old broken port. You held down the volume and power ( It will boot to recovery mode). As the boot loader is locked by default you are sticked in boot loop. When the above mentioned process is completed. Connect the battery and hold on ONLY power button for 1 minute. It will exit recovery.

Agreeing that you have expertise in hardware swapping and also assuming software expertise, reinstall all the parts and perform the clean install of the MacBook using a USB keyboard and mouse and perform clean OS X install as it might suffered kernel panic or kernel extension problem. Before reinstalling clean the connectors of the trackpad and keyboard in the logic board with ipa. All the best

If you are sure that the screen is a reputed one, remove the screen flex and rearrange and install brackets(assuming if you missed it in case). Lock the flex cable carefully.