Help Requested - Strange Mi3 64gb Behavior

[Mark123]

Hello!

Thank you for reading.
My Mi3 64GB (MIUI-4.3.14) is behaving in very strange ways and I wondered if you could help me. I would love it!

• Unable to reliably access the same pictures/media. So when I go to use a messaging app for example and I want to send a picture, I get different pictures every time I access it. Thus if I took a picture now and wanted to send it to you, I'd possibly not get access to it. But if I press try to access it again via the same app, it might show up.
  
  
• When backing up my pictures and videos, I choose to use the import option. After importing, I make sure the pictures get deleted. Yet when I go back to using my phone, all the pictures are still there! (Yet they're also backed up. At least some of them.) This ties in with point 1. When I did the first import, the import program on Windows found 5500 images and possibly videos. When I imported all those and checked "delete after import", I tried again. This time the program found around 8000. Rinse repeat. I did it again and this time the program found nearly 12000 items! What's going on? I seemingly can't empty the SD card storage.
  
  
• My language settings are also messed up. I seemingly can't switch back to an English version. So all the menu-items are in Chinese. Yet to start with, switching worked fine.
  
  
• Data and WiFi connectivity, as well as vibration, will randomly turn themselves on. Sometimes GPS too. Even though no apps have permission to do this, I think. I think this is highly annoying. I mean if you turn something off or on, you expect it to stay that way.
  
  
• Sometimes while using a chatting app, the built-in keyboard will sometimes become VERY sluggish, by not responding to presses, being delayed or recording incorrect presses. So if I press A, it might send a V for example; that sort of thing. Yet I don't have a lack of RAM or anything.

Thanks for the help

P.S. How do I update my Mi3 to the newest versions?

P.P.S The built-in Backup is so odd, because it can only back things up to my own storage; but I've got to no space left.