Neon Tetra ?s and Guppy ?s

I have two questions:

I have one neon tetra. I recently added two more neons to the community tank. They've disappeared, most likely eaten. I've added more in the past but it's always the same problem.

I know that neons need schools so would about three or so neons be okay in a small tank with wild guppies? Or would one be okay with guppies since they're about the same size or is there no chance at all he would school with them?

And, are guppies labyrinth breathers or do I need to put an aerator in there? Or can a filter aerator the water sufficiently? After the first batch of fry become adults, do I need to make sure I take out the males? Or can I have more than one male in the same tank?

What is the smallest filter I could use? I don't like that small greenish clear one, it's too noisy. The nano filters are too expensive relative to their size. The only one I can think of is a stingray filter but the smallest is up to 5 gallons and their tank isn't that large.

I'm not sure which tank you're talking about. The community or the guppy tank.

The guppy tank is 2.5 gallons and all I have in there are wild guppies. I have two females and one male and one batch of fry.

Hmm.. For some reason I'm not getting notifications through my email.

Anyways, I am cycling the 2.5 gallon. Why is it overstocked? These fish are tiny and there's plenty of room to spare.

Is the Azoo palm filter also biological and chemical? Is it better than this? http://www.petdiscounters.com/c15/c70/c244/Economy-Corner-Filter-p646.html . I like that the filter you suggested isn't a submersible. I don't like taking up valueable space with a blocky filter.

My other gallon is a 40 gallon or maybe more with (every is going to call me on overcrowding):
1 bala shark
1 glass catfish
1 upside down catfish
2 african glass catfish
5 feeder goldfish
1 neon
four mollies
1 upside down butterfly fish
2 cherry bars
1 black skirt tetra
2 tetras
2 albino cories
2 pointy tailed catfish
1 hatchet fish
2 whiptail catfish

PLEASE don't yell at me! I keep all my aquariums very clean and my parents won't let me get a bigger one.

The last time I lost a fish was during the summer. I almost never have fish die on me.

I forgot to say how long they've been set up. The large community has been set up almost 20 years ago.

The guppy tank was set up about a month ago.