Alright so IPB got back to me, and said it's not possible unless I have a full backup.
Unfortunately, I only ever made full SQL Database backups, not 100% of the entire site. Therefore it looks like we're stuck with 3.4.3
Selective Quoting: This has been fixed, and no longer displays <span itemprop= instead of the person's actual name. In addition, the button has been removed and a small menu shows up when you highlight text.
@Mention: There are two versions of this plugin. One which hasn't been updated since 3.2, and another more recent one for 3.4. I have bought and tried both of these, and neither works when you click on the link underneath a person's avatar. However, when you highlight text you have the option to either mention that person, or selectively quote the text. Mentioning someone this way works perfectly fine, as well as just typing in someone's username after an @ symbol. Though if you type it in manually, their username isn't all colored and nice as if you did it through highlighting text (they still receive the notification).
Mobile Devices: Sad to say that I have no idea when and how this will be fixed. I'm not the one to stand around and wait for a fix though, especially how this hinders a few people from posting on the forum. I'll be actively perusing a solution for this problem.
Mark forum as read: Low on the priority list, as there are more important things that need to be fixed.
No emotes in posts: Low on the priority list, as there are more important things that need to be fixed.
Just fixed the emotes issue actually.