Several questions regarding FlashForge Adventurer 3 Pro

Hi all! First post!
Last night I picked up a used Adventurer 3 Pro with some known issues. This isn't my first 3D printer, but there are some things I'm confused about that hopefully you can help with.

1) The bowden tube coupling that is supposed to grab onto the filament guide tube doesn't grab at all, despite pushing it up, pushing the hose down and then pulling it up. Can I assume that it's supposed to really grab onto the hose and hold it tightly in place? Without the filament guide tube being locked in place, the filament isn't being pushed down into the hot end.
2) Is the filament's only way of being pushed into the hot head accomplished by the filament roll take-up motor found on the right side of the case? (My finder "pulls" the filament through from the head, rather than being "pushed".)
3) A previous owner seems to have printed a new bottom plate for the area around the hot head that doubles as a plate to hold the hot head release buttons in place as well as being some kind of weird air venting contraption. Does anyone know what that's all about? I've ordered an entirely new head assembly because it's probably cheaper to replace the whole thing than the individual parts.
4) I honestly don't understand how you're supposed to remove your builds! The bottom (heated) plate seems to be a solid piece of glass with a coating on it that only looks to be removable by bending the tabs that are holding the plate in place. The manual describes "pulling the plate out", but mine has no such capability that I can see. To be clear, my build plate is a solid piece of glass with a coating on it rather than anything the seems to be removable. Getting builds off that plate (if I get that far) is going to be tricky!
5) The filament feeding motor and wheel has a thumb lever that can be pushed to separate the rollers that push the filament in. Yet that thumb lever is completely out of reach, being hidden behind the case. I have a hard time believing this is by design. Does anyone have a clue how you're supposed to manually separate the rollers without removing the entire filament feed motor assembly?
I've attached some photos of the things mentioned here. Unfortunately, it looks like they are being displayed rotated... hopefully you'll know what "up" is!
-Pete
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