Do my platies really need all this?

Question
I bought 4 platies yesterday. I really wanted to wait and see if they adjust to my home and simply are able to make it the 1st 24-48 hours before I go spending a bunch of money to set up the entire project..so..I placed them in an upright glass cylinder 10" tall by 5" diameter, it has very thick glass, 1/4 " thick. I think that would be about 1 gallon of water...I placed stones at the bottom and one plastic plant.  Then I filled with filtered tap water..let them acclimate in the bag of water for 20 minutes and then put them in. Also placed a thermometer on the glass, temp is a steady 76. I have not tested the water, do not yet have any of that equipment. I fed a little last night and they ate..Then today I overslept so I fed them at noon, then a snack later and then a little bit again at night. I know I shouldn't feed 3 times but they were very small portions..I intend to feed twice daily, am and pm. They seem to be doing fine so far. But one of them was kind of lagging around at the bottom and refuses to eat today, so tonight I put in an air pump.

My questions are the following:

1) Do I really need to get a bigger tank?  What will happen if I don't?

2) Since it is a small tank, easy to handle, I am changing 50% water everyday..started today..is that ok?

3) The air pump makes tons of noise and covers the entire surface with bubbles (since it really is intended for a 5 gallon tank) The noise bothers me..can I use something else instead?  Could I just turn the pump on only for a few hours each day?? They do seem to like it though, 3 of them, including the lagging one went straight to the bubbler and are next to it right now..So I'm thinking they were oxygen deprived...will it bother them now that their entire surface area is covered by bubbles? one more thing, as soon as I turned on the air pump, it stinks!..I don't understand why since I just changed their water like 5 hours ago..Why does it stink? is there anything I can do about it? I have them right next to my bed so I can watch them and so the stink is going to be with me all night...

4) I read on this website its good to get a filter..and that would take care of the oxygen too? Then why doesn't everyone just get the filter? Why would anyone buy just the air pump? I'm confused...

5) My small platy that was lagging, alternately shakes a lot..shakes and shakes really fast..and now he's got the other small one doing it..what does it mean?..both of the smaller ones are whiteish in color..the bigger orange ones seem to be just fine..is there a color that reflects better health?

6) how do I prevent them from breeding? I really am happy with just my four.

Thanks soo much!!

Answer
Hello!

1) Yes, they will be overcome with disease if you don't. Growth will be stunted, regardless of water quality.

2) That is good until you get a bigger tank

3)+4) Air pumps are useless. Replace it with a filter. You can get an AquqClear hand-on back filter for $20 and it will provide oxygen as well as clean your tank. I don't know why everyone doesn't just get the filter. Some people just aren't too bright I guess.

5) That is likely dropsy. He is already not liking the small tank. It may go away, but if it doesn't there is nothing you can do. Don't worry it isn't contagious. You can try putting a little aquarium salt in if you would like.

6) LOL, you can't. IF you have all females, then they will not breed. However, it is likely that if you have no hiding places in your tank the other platies will eat the babies.

-Nick