2 things: your surface 3 has 64GB of storage, not RAM. While it may seem like a rather nit-picky distinction, it is rather significant. Basically, RAM affects performance if you don't have enough, storage is how many files you can store (your C drive) Regardless, the RAM on all surface models is soldered to the motherboard and not upgradable. Surface Pro models have removable SSDs that can be replaced to add more storage but you have to remove the display first, a difficult process that usually requires replacing the display completely. Surface (non-pro) models have their storage chips soldered to the motherboard, preventing replacement.
You can see if Apple will repair it (this problem should be covered under warranty) but if they won't all you likely have to do is put a little lubricant in the hinge, something that is fairly easy to do if you have the right tools.
I recommend isopropyl alcohol. I've used it on multiple dirty computer components with no negative effects. Not only does it not damage components due to its low water content, but it cleans very easily and is readily available at almost any drugstore. I suggest 90%+ but 70% works fine in a pinch. Edit: Use a Q-tip or fine cloth to apply it
It is either the charger or the port itself. Check the charger using a multi meter (if you don't have one you probably know someone that does, or you can buy one online for cheap. If the charger is fine then it is the port which is usually separate from the motherboard and fairly cheap to replace.
Use an adapter and plug it into your computer to make sure it is the SD reader on your phone. If it is the SD reader then there's not much you can do without a rather costly replacement as the slot is part of the motherboard.
This sounds like a blown capacitor, diode, or other similar component. There is a strong possibility that your hard drive is still working. Disassemble the computer using one of the many guides on this website and remove your hard drive . Put the hard drive in an external dock (you can buy them online for ~$20) and attach it to another computer to extract the data. Alternatively you can find the circuit board with the damaged component by looking for burn spots surrounding a missing or damaged component. Once you locate the damaged circuit board you can try replacing it. Keep in mind that if part of the power supply is damaged then it probably took the other components with it like the motherboard, processor, and even hard drive. Because of this possibility I highly recommend checking to see if the hard drive is working before you attempt a full system repair.
The only things you can't move from the C drive are the core Windows files. Things like your Steam library (or any other games), movies, pictures, documents, downloads, and almost any installed program can be moved. Keep in mind that any program you move with a shortcut will need to have the shortcut location changed. I highly recommend a small program called WinDirStat to help you determine what is taking up the most space. It constructs a visual representation of the contents of your hard drive, very handy for situations like yours.