Which of these hair dyes do you recommend and which color from each, if any?

How light was the hair under the green? How many times did you bleach it to get that colour?
The trouble with bleaching over already bleached hair is that bleach damage is cumulative and permanent. So if your hair is already close to it's limit, another full bleach may be too much and cause breakage etc.
So i would separate the hair and bleach only the virgin parts, if you need to lighten the already bleached parts use a very low vol for a short time or a bleach bath.
The only two brands i have used myself from that list are Crazy colour and Directions. For greens Directions Alpine and apple green are both really good, Alpine is much bluer. Crazy Colour Pine Green is also a nice dark blue toned green, longer lasting than a lot of their shades. Peacock blue is also quite teal/green especially on yellowy hair, but not quite as long lasting as Pine green IME

Not too light I guess. It seems like every time I dye my hair it gets darker and darker. but maybe that's just me.

I bleached it once. I planned on bleaching it several times but my stupid roommate decided she wanted to learn about hair and stuff and asked how hard it was to bleach hair, I said it's pretty simple, you just put the stuff in the hair EVENLY and let it sit. She put so little that 3/4 of the bottle was still there. I was like, why? Well you said to save some for the roots. Some!!!! The roots are just a tiny portion of the overall hair. Gah.

So after the max time was up, it was a horror mix of orange and yellow and whatnot, and I didn't have the stomach to keep it like that for a few weeks before I could bleach again and just got a green thinking it would look fine no matter what, even if some parts are darker/lighter, it'll all be green. So that part was fine, but then I haven't bleached it since (5 months ago) and just kept dying it as soon as it wore off and it looked fine, but now I'm out of my usual green hair dye and stuck abroad longer than I intended so that's all I have to work with apparently.

My hair is pretty strong in general (as hairdressers have told me, though I rarely go but once she was amazed how long it took my hair to dry and it's pretty voluminous and thick even though I thin it out) so I guess that's a good thing though I never seem to have the dye last the full 4-6 weeks they usually claim and I've read all sorts of remedies for making it last longer like vinegar rinse and coconut oil.

I'll see if I can get my sister to help, she actually knows how to work with hair so I'll have her separate the parts which I was hoping I wouldn't need to cause then I can just do my hair myself when I have time without assistance, but she's good. If I were to bleach all of those separately or lets say just strip what I've got as much as I can when it runs low on color, and if I were say to get a variety of directions, say, turqoise, lagoon blue, and alpine green, and do different strands a different color, how would I best go about doing that and make it look good and not like it's botched up? And when it fades, would each color fade differently and make it look weird?

I always see cool pictures like this on the internet but never in real life as I always assume it's done as a one day photo shoot and the hair doesn't last long after that, but if one were to try and attempt a layering of colors, how would they best achieve that?

Why would you assume that would only last one day? totally possible with the right products and hair care routine to maintain a multicoloured look.
If your base is patchy you need to go through it section by section and apply the bleach to the darkest areas first in order to get it even. This is actually quite difficult, much more so than bleaching virgin hair.
Many people here do their hair entirely alone, all you need is two mirrors. If I were your sister i certainly wouldn't be volunteering to help after the way that you blame your roommate.

I never said it would last a day, just that I assumed it wouldn't look as good for long.

Also, my sister has helped me plenty before, as has my mom and another friend and all have done fine with bleaching my hair. I never blamed them for anything because they followed directions well or already know what they were doing. I don't see it as a hard process.

I blamed my roommate because she really did a bad job not because I'm just saying that because I don't want to put any blame on myself. I should have done the job myself, I understand that very well. I just explained clearly to make sure it's even, which it wasn't at all, some parts weren't even covered as I'd have liked and I had to tell her to go over them and told her exactly how I wanted things. I explained it like she was five as best as I could so that it would be a simple process.

Im sorry, but that still comes across as being really ungrateful and judgemental. I feel sorry for your roommate. If you knew certain parts weren't covered properly, why didn't you add more product at that point?

I just said that we did, I told her to add more. But I don't think I realized how little she added overall. I also never said to her face that I was upset or angry or anything. I'm thankful she wanted to help and told her that people make mistakes and learn from them, I didn't flip my shit or yell at her. Of course I was irritated I didn't get what I wanted, but I was never ungrateful for the help, even if imperfect. But ultimately it was her fault for not listening to my directions when I told her to apply liberally and make sure everything is covered evenly.

No, you just slated her on a forum instead.
You would get more help and advice here if you lose the attitude.

I just said that we did, I told her to add more. But I don't think I realized how little she added overall. I also never said to her face that I was upset or angry or anything. I'm thankful she wanted to help and told her that people make mistakes and learn from them, I didn't flip my s**t or yell at her. Of course I was irritated I didn't get what I wanted, but I was never ungrateful for the help, even if imperfect. But ultimately it was her fault for not listening to my directions when I told her to apply liberally and make sure everything is covered evenly.

Who's a sulky baby then?

Oh, and with your behaviour, I'd say none of them. Why you couldn't be bothered to tell your roommate what the problem was at the time, I don't know.

Grow up and get out!