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I missed how you connected the two radios to eachother and transmitted between them -- ouch! Remember, the receiver section is made to amplify microvolt level signals from the antenna, but the transmitter section puts out at least 10,000 times that level. But the fact that you were using an underpowered power supply and that you were able to send and receive signals, maybe your rigs are still OK. Hopefully!
Listening: long wavelengths go better at night and short ones during the day, so 80m at night, 40m late evening/early moring, and 20m during the day are optimum times. Of course closer stations can communicate with these frequencies at other times too. You should look at the ARRL band plan (google it) to see what frequencies to listen on and for what. But even with your short antenna, you could be able to hear CW and SSB voice pretty easily.
Do you have a radio license yet? Studying for the tests should give you the background you will need to start really understanding and enjoying the amateur radio bands and practices/procedures.