Definitely wouldn't use that battery, unless you're looking for fireworks
The wing might not be the right choice for a starting plane, but I applaud your tenacity!
Also, I don't recommend night flying to start off with.
The guys are right though, battery's history! Put that battery in a bucket of water, add salt and let it sit for a few days. It will discharge it to zero so it will be safe to dispose of after that, but it's toast. Do not try to use or charge it.
Oh gosh - I'm sorry I just was in fits! You are very brave to be doing your first flights with a twitchy looking wing in the dark.
So cool - you posted this. My first flight was into a tree... will be looking out for your new flights now you've had a months practice!
They could be replaced with a single central rudder.
Alternitively, for a clean look, others have made their wings with draggy wingtips, a pair of which do the same as any fixed V-stab will do. I've seen the effect and understand the descriptions, but dont' know the finer points to give you the sure-fire build technique.
I'm a noobie too, but might there be a balancing issue going on with this plane? At one point it sounded like the pilot said he wasn't doing anything to the controls, but the plane was still tracking all over the place.
Um, yes they do, they play a role in your yaw control. Try to keep the wings level and remember which way is up and which way is down on your sticks. Also try to maintain your throttle, only use full if even, on take off. This is really important: Have someone launch it for you. A lot of your crashes occurred on take off, and it is best for beginners to have both hands on the sticks. Also try to stick to daytime, your second video was fine. Night flying is a much more difficult way to fly, especially without lights on the model. Best of luck to you and your new hobby!