I am fairly sure that you can't replace the memory card (correct me if I'm wrong) The memory card is usually soldered (embedded) into the Main Board. There is no way of replacing the memory card without some soldering skills. Visit a certified technician for more accurate answers.
If the keys are still intact, you can orient them properly on their respective places and press towards them, else buy new keys from any online or physical shop. There is no need to buy a new laptop or visit any technician, since fallen keys are just usually popped off from their places and not broken.
Unfortunately, the Mac Mini Late 2012 has a limitation to 1600MHz, which in my opinion is more than enough for most day-to-day needs. You can even save a few bucks by purchasing 1600MHz RAM instead of 1866MHz RAM.
This is a common problem in most Galaxy phones, #Make sure the replacement battery is original and not a knock-off (1) Try not to run many apps at the same time (2) The phone (or the battery) could not be faulty, the Galaxy Grand is supposed to operate for 3-4 hours with a Li-Ion 2100 mAh battery (3) Consider buying an external power bank (battery) This power bank should last with you for a good 15-20 hours before needing to be recharged.
The iPad could have sustained a powerful shock. Connect it to the 10watt charging block it came with, and wait to hear for the charging sound(it's okay no to hear it). Wait for at least an hour, then proceed with the following: #Make sure to disconnect the iPad from the charging outlet (1) Hold the power button for 30 - 60 seconds (2) The Apple Logo should appear, if not repeat several times or charge the iPad (3) After the iPad shuts off release the power button and reconnect it to the charger (4) wait for 10 - 30 seconds, if the Apple Logo did not appear, hold the power button until it does If the above did not work, then you should visit a certified technician.
I strongly advise you to encrypt your phone's data before resetting it to factory settings. Deleting all the files does not actually delete them all, anyone with a spare hour or two can extract deleted information from the phone. By encrypting your phone you make sure that even if he/she got the deleted data, the data would be useless. To encrypt: 1. Go to "settings" 2. "General" (skip if old settings layout) 3. "Security encrypt device" 4. Make sure it is connected to a charging outlet To reset 1. Go to "settings" 2. "General" (skip for old settings layout) 3. "Backup and Reset" 4. Uncheck "Automatic Restore" 5. "Factory data reset" 6. "Reset Device" Done P.S It is advised you encrypt your phone twice or more, but if you are an impatient person, you may encrypt it once, which should be enough. Not all Pre-Owned phone buyers are looking to extract data from your phone.